What are the best practices for a commercial diver to ensure their own safety during a deep dive?

Ensuring safety during a deep commercial dive requires rigorous adherence to surface-supplied protocols, physiological management, and tight communication with the dive team.

• Surface-Supplied Gas Management: Rely on surface-supplied air or mixed gases (like Heliox or Nitrox) rather than scuba, ensuring a continuous, monitored gas supply with a reliable bailout bottle on your harness. Continuously monitor gas partial pressures to avoid hypercapnia, nitrogen narcosis, and high-pressure nervous syndrome (HPNS).
• Rigorous Pre-Dive Checklists: Perform comprehensive surface checks of your umbilicals, communications gear, pneumofathometer, and hot-water suits (if diving in cold depths). Double-check that your helmet or bandmask and all gas-train connections are secure and pressure-tested.
• Strict Decompression Scheduling: Adhere meticulously to approved decompression tables (such as U.S. Navy or company-specific algorithms). Utilize in-water staging or a bell-bounce/saturation system with a deck decompression chamber (DDC) ready on the surface to manage long or omitted decompression profiles safely.
• Continuous Surface Communication: Maintain clear, uninterrupted voice communication (two-way comms) with your topside dive supervisor. Report your physical status, depth, and task progress at mandatory intervals, and immediately notify the surface of any signs of disorientation or equipment glitch.
• Thermal and Environmental Protection: Deep water drops in temperature rapidly. Wear properly fitted hot-water suits or drysuits to prevent catastrophic core hypothermia, which impairs cognitive function, manual dexterity, and the body's ability to off-gas inert nitrogen/helium safely.
• Emergency and Contingency Readiness: Know your emergency protocols for umbilical entrapment, gas contamination, or blowout scenarios. Ensure the standby diver is dressed, geared, and prepped in the "ready" position on deck at all times during active deep operations.

You can reference specialized field manuals like The Commercial Diver's Handbook or standard protocols outlined by the Association of Diving Contractors International (ADCI) for regulatory compliance.

If you're looking into specific operational depths or diving techniques, let me know if you are focusing on air/nitrox surface-supplied diving, saturation diving , or mixed-gas deep procedures so I can tailor the safety protocols further.

Deep commercial diving is a high-risk, team-dependent operation. The diver's personal safety starts before entering the water and depends heavily on the supervisor, tender, standby diver, life-support system, and emergency plan. OSHA specifically requires pre-dive planning to address hazards, gas supplies, equipment, diver fitness, decompression, and emergencies.

Key safety practices

• Use the correct dive plan and depth limits. Never exceed the planned depth, bottom time, gas exposure, or decompression profile. Deep dives can involve nitrogen narcosis, oxygen toxicity, high-pressure effects, and decompression sickness.
• Conduct a thorough pre-dive briefing. Confirm the work scope, depth/time profile, currents, visibility, temperature, entanglement hazards, equipment hazards, communications, gas changes, decompression plan, and emergency procedures.
• Know your breathing-gas supply. Verify the primary supply, reserves, gas composition, pressure, and switching procedures. For surface-supplied deep dives, OSHA requires sufficient primary gas for the planned dive and decompression, plus additional reserves for applicable deep dives.
• Never dive without effective surface support. Maintain continuous communication and tending as required by the diving mode. A properly equipped standby diver should be ready to respond immediately on deep surface-supplied operations.
• Inspect and function-test life-support equipment. Pay particular attention to breathing-gas systems, umbilical, helmet/mask, bailout/reserve supply, communications, harness, weights, and emergency equipment. Don't accept equipment with an unresolved defect.
• Control the worksite, not just the dive. Deep commercial divers may face cranes, intakes, pipelines, propulsion systems, electrical equipment, welding, hydraulic equipment, and other energy sources. Isolate hazardous energy and coordinate with everyone working around the dive. OSHA specifically highlights coordination with nearby activities.
• Treat the umbilical as a critical lifeline. Avoid sharp edges, pinch points, entanglement, excessive bends, and snagging. Maintain awareness of its routing and communicate immediately if its condition or position changes.
• Manage workload and breathing. Avoid unnecessary exertion, maintain controlled breathing, and recognize early signs of fatigue, CO₂ buildup, narcosis, hypothermia, or impaired judgment. At depth, seemingly minor problems can escalate quickly.
• Follow the decompression procedure exactly. Maintain the prescribed depth-time profile and gas changes. Don't improvise ascent rates or decompression schedules. OSHA requires applicable decompression tables to be available and the diver's depth-time profile to be maintained.
• Have a rehearsed emergency response. Know exactly what happens for loss of gas, loss of communications, umbilical damage, entanglement, loss of orientation, runaway descent/ascent, contaminated gas, medical emergency, or loss of the working platform. Emergency procedures should be established before the dive, not invented underwater.
• Take post-dive symptoms seriously. Report unusual fatigue, joint pain, dizziness, weakness, numbness, breathing difficulty, confusion, or other abnormal symptoms immediately. Commercial diving procedures require post-dive assessment and instructions to report possible decompression-sickness symptoms.
• Know the medical evacuation plan. Before diving, the team should know where the appropriate hyperbaric facility/chamber is, how to contact emergency medical support, and how the diver will be transported.

A particularly important principle

Don't let production pressure override a safety stop. A commercial diver should be empowered to stop the operation if gas supply, communications, equipment, environmental conditions, decompression control, or physical condition becomes unacceptable.

For U.S. commercial diving, the governing OSHA requirements are in 29 CFR Part 1910, Subpart T; for offshore operations, the current IMCA International Code of Practice for Offshore Diving (Rev. 3.3, March 2025) and applicable ADCI consensus standards are useful additional references.

For an actual deep dive, these general practices do not substitute for the dive supervisor's approved dive plan, the applicable decompression tables, formal commercial-diver training, and site-specific procedures.

For a commercial diver performing a deep dive, safety depends on disciplined planning, reliable equipment, strong team communication, and strict adherence to dive procedures. Deep commercial dives add risks such as decompression illness, gas supply problems, entanglement, poor visibility, cold stress, and underwater work hazards.

Before the dive

• Conduct thorough dive planning

• Review depth, bottom time, decompression requirements, task hazards, weather, currents, visibility, water temperature, and emergency procedures.

• Perform a job hazard analysis and ensure all team members understand their roles.

• Verify diver qualifications and fitness

• Ensure the diver is trained and qualified for the specific depth, breathing system, mixed-gas procedures (if applicable), and work task.

• Do not exceed personal training, medical, or operational limits.

• Inspect and test all equipment

• Check helmet/mask, regulators, communications, gauges, bailout system, umbilical, harness, gas supply, tools, and emergency equipment.

• Confirm maintenance records and equipment readiness.

• Confirm emergency readiness

• Have a standby diver, surface support, first-aid capability, emergency contacts, and access to appropriate medical support or recompression facilities when required.

During the dive

• Maintain constant communication

• Keep reliable voice communication with the surface team whenever the diving system supports it.

• Report status changes immediately: gas supply, visibility, equipment issues, fatigue, or hazards.

• Monitor breathing gas continuously

• Track primary gas supply, reserve/bailout supply, depth, and time.

• Know the planned point for ending the dive and begin ascent before reaching critical limits.

• Control ascent and decompression carefully

• Follow the approved decompression plan and procedures.

• Avoid rapid ascents and report symptoms such as joint pain, dizziness, unusual fatigue, numbness, confusion, or breathing difficulty.

• Manage the umbilical and surroundings

• Prevent kinks, snags, and entanglement.

• Be alert for hazards such as moving machinery, sharp edges, structures, and differential pressure zones (for example, intakes, pipes, or valves).

• Use the stop-work authority

• End or suspend the dive if conditions become unsafe: equipment failure, loss of communication, unexpected current, poor visibility, contamination concerns, or changing work conditions.

After the dive

• Perform a post-dive health check

• Report any symptoms or unusual sensations immediately.

• Follow procedures for decompression monitoring and medical evaluation if needed.

• Inspect and maintain equipment

• Record problems, damage, and repairs before the next operation.

• Debrief the team

• Discuss hazards encountered, equipment issues, and improvements for future dives.

A key principle in commercial diving is that the diver is never operating alone: the supervisor, tenders, standby diver, surface crew, and diver all share responsibility for maintaining a safe operation.

Ensuring safety during a deep commercial dive—typically utilizing surface-supplied breathing apparatus (SSBA) or saturation techniques—requires strict adherence to operational protocols, physiological limits, and team communication.

Essential Safety Best Practices

1. Rigorous Pre-Dive Systems Checks & Equipment Inspection
   • Conduct comprehensive surface checks of the gas supply, pneumofathometer, communications gear (hardwire comms), and hot-water suits.
   • Verify redundant gas supplies (bailout cylinders) are fully charged, functionally tested, and correctly mounted before leaving the bell or stage.
2. Strict Gas Management and Monitoring
   • Continuously monitor partial pressures of oxygen (PO₂) to prevent hyperoxia or hypoxia, especially when shifting gas mixes (e.g., Helium-Oxygen/Heliox or Nitrox transitions).
   • Maintain constant communication with the surface compressor/gas rack operator to track bottom time, gas consumption rates, and tissue-gas loading limits.
3. Adherence to Decompression Schedules
   • Follow approved decompression algorithms and tables (such as the U.S. Navy Diving Manual ) precisely.
   • Never rush ascents or omit scheduled stops; utilize in-water staging or a hyperbaric deck decompression chamber (DDC) as required by profile depth.
4. Active Thermal and Environmental Management
   • Maintain thermal protection (active hot-water suit delivery) to stave off hypothermia, which rapidly impairs cognitive function, manual dexterity, and decompression efficiency at depth.
   • Secure yourself against strong currents or drop-offs using proper umbilical tending techniques and staging lines.
5. Flawless Surface-to-Diver Communication
   • Keep a continuous, clear verbal loop active between the working diver, the standby diver, and the diving supervisor. If comms fail, execute pre-agreed line-pull signals immediately or abort the task.

If you're looking into a specific operational context, let me know:

• Are you focusing on surface-supplied air/heliox or saturation diving?
• Are you looking for specific guidelines on decompression sickness management or equipment redundancy?

For a commercial diver, especially on a deep or decompression dive, personal safety depends less on individual skill alone and more on disciplined adherence to the dive plan, the dive team, and emergency systems. OSHA's commercial-diving rules emphasize planning, gas reserves, communications, decompression procedures, standby capability, and emergency preparedness.

Key best practices

1. Never improvise the dive plan

   • Review the job hazard analysis, maximum depth, bottom time, environmental conditions, gas plan, decompression schedule, and abort criteria before entering the water.
   • Confirm everyone understands their role and the emergency procedures.
   • Stop or reassess if conditions materially change. OSHA specifically requires assessment of environmental hazards, gas supplies, equipment, fitness, decompression, and emergencies.

2. Treat breathing-gas management as mission-critical

   • Verify the primary supply, reserves, gas composition, pressure, and supply duration before the dive.
   • For deep surface-supplied dives, ensure the required reserve breathing gas is available to the diver and at the dive location.
   • Don't continue working simply because gas remains if another part of the plan says it's time to terminate.

3. Maintain reliable communications

   • Test two-way voice communications before descent.
   • Maintain communication with the surface throughout the dive and report changes in condition, equipment problems, visibility, workload, or symptoms immediately. OSHA requires operational two-way communications for surface-supplied and mixed-gas operations.

4. Respect decompression discipline

   • Follow the applicable, authorized decompression procedure exactly; don't shorten stops or alter the profile because you feel fine.
   • Maintain an accurate depth/time profile, including breathing-gas changes.
   • Remember that mixed gas and helium reduce some problems associated with nitrogen at depth but do not eliminate decompression risk.

5. Know the emergency plan before you need it

   • Know how to respond to loss of breathing gas, umbilical problems, loss of communications, entanglement, equipment failure, loss of visibility, runaway ascent, and medical emergencies.
   • Know where the decompression chamber is and how long it takes to reach it.
   • For dives requiring it, OSHA specifies chamber capability and requires appropriate treatment equipment and trained personnel.

6. Use the standby diver and surface team properly

   • A standby diver isn't merely a person "on call"; they need to be appropriately equipped and ready to respond.
   • For surface-supplied air dives deeper than 100 fsw or outside no-decompression limits, OSHA requires a standby diver and additional gas provisions.

7. Control worksite hazards underwater

   • Identify entanglement, crushing/“Delta-P,” current, vessel traffic, contaminated water, suspended loads, hydraulic/pneumatic equipment, electrical hazards, and welding/burning hazards.
   • Never assume that a familiar worksite is safe simply because you've dived there before. OSHA identifies commercial divers' exposure to construction, demolition, power-tool, material-handling, and other hazards in addition to ordinary diving hazards.

8. Monitor yourself for impairment

   • Deep diving can produce nitrogen narcosis and other pressure-related effects, while cold, exertion, fatigue, and stress can compound impairment.
   • If you're confused, unusually fatigued, cold, short of breath, nauseated, experiencing unusual pain, or otherwise impaired, tell the supervisor and terminate/abort the dive according to the emergency plan rather than trying to push through.

9. Take post-dive monitoring seriously

   • Report any unusual symptoms after the dive, even if they initially seem minor.
   • For certain deep, mixed-gas, or decompression dives, OSHA requires the diver to remain awake and near the decompression chamber for at least an hour after the dive.
   • Don't fly or travel to altitude after diving unless the applicable diving medical guidance and company procedures permit it.

10. Use a formal safety culture—not “hero” behavior

• A commercial diver should be willing to call a dive, stop work, or request a reassessment without pressure to continue.
• Current IMCA guidance likewise emphasizes competence, planning, diving medicine, environmental conditions, communications, gas handling, documentation, and emergency procedures.

The most important principle: on a deep commercial dive, your safest decision is often the decision made before you enter the water. If the gas plan, decompression plan, communications, equipment, standby capability, environmental conditions, or emergency response aren't satisfactory, don't enter the water until they're corrected.

For U.S. commercial diving, the applicable OSHA requirements are in 29 CFR Part 1910, Subpart T; other jurisdictions and offshore/marine contractors may impose additional requirements.

Ensuring safety during a deep commercial dive requires strict adherence to regulatory standards (such as OSHA Commercial Diving Operations Regulations or IMCA Guidelines ), flawless communication with the surface, and meticulous equipment management.

Operational Planning and Hazard Identification

• Job Safety Analysis (JSA): Conduct thorough pre-dive briefings detailing the operational scope, environmental factors, and hazard assessments.
• Delta-P (Differential Pressure) Awareness: Identify and map out any potential suction or pressure gradients (Δ P) near pipes, valves, or dams, ensuring strict lockout/tagout (LOTO) protocols are executed before entering the water.
• Emergency and Contingency Planning: Verify that a medical emergency plan, dedicated oxygen equipment, and a functional recompression chamber are staged and ready on-site before splashing.

Surface-Supplied Systems and Umbilical Management

• Strict Reliance on Surface Supply: Utilize surface-supplied air or mixed-gas diving configurations (such as heliox or trimix for extreme depths) rather than independent scuba, ensuring an uninterrupted and monitored gas supply.
• Umbilical Integrity and Tending: Maintain constant awareness of umbilical tension and position to prevent snagging on subsea structures, wrecks, or debris . The topside tender must continuously monitor and manage the slack.
• Continuous Communications: Rely on uninterrupted, clear two-way voice communication with the topside dive supervisor . Acknowledging verbal check-ins is mandatory at designated intervals.

Physiological and Decompression Protocols

• Gas Mix Management: Rigorously test and analyze breathing gas mixtures prior to the dive to eliminate risks of hypoxia, hyperoxia, or acute oxygen toxicity.
• Inert Gas Narcosis and HPNS: Monitor for signs of nitrogen narcosis or High-Pressure Nervous Syndrome (HPNS) when breathing helium-based mixes at deep profiles, communicating any cognitive slowing or tremors immediately to the surface.
• Adherence to Decompression Schedules: Strictly follow computed ascent rates and staged decompression profiles (or saturation living protocols) to avoid decompression sickness (DCS).

If you are working on a specific project, let me know:

• What is the planned depth and bottom time?
• Are you using surface-supplied air, nitrox, or trimix/heliox?

I can provide more targeted guidance on the relevant decompression models or safety checklists.

Executing a deep commercial dive requires rigorous planning, adherence to strict regulatory standards (such as OSHA Commercial Diving Standards and Association of Diving Contractors International (ADCI) guidelines), and absolute synchronization with the surface team.

The essential best practices to ensure personal safety during a deep commercial dive include:

1. Pre-Dive Planning and Briefings

• Comprehensive Dive Plan: Formulate a written, site-specific dive plan covering maximum depth, bottom time, breathing gas mixtures, decompression schedules, and emergency contingencies.
• Job Hazard Analysis (JHA): Conduct a thorough tailgate or toolbox safety meeting with the entire dive crew to identify environmental factors (tides, currents, visibility) and operational hazards.
• Fitness and Readiness Verification: Ensure personal and crew fitness, confirming adequate rest and no lingering physiological or psychological deficits that could impair judgment under pressure.

2. Equipment and Gas Management

• Rigorous Equipment Inspection: Inspect all components of the surface-supplied diving system (SDDS), helmets, harnesses, thermal protection, and pneumofathometers prior to entry.
• Gas Purity and Reserves: Verify that primary and secondary (reserve) breathing gas supplies on the surface and diver-carried backups meet volume and purity requirements (with compressor air quality tested regularly).
• Thermal Protection: Maintain adequate thermal defense (such as hot-water suits), as rapid heat loss at depth accelerates fatigue, narcosis susceptibility, and decompression stress.

3. Umbilical and Communication Protocols

• Continuous Tend and Communication: Maintain uninterrupted, two-way voice communication with the surface control station and ensure the diver is continuously tended by a dedicated dive team member.
• Umbilical Awareness: Constantly monitor the location of the air supply umbilical to prevent pinching, snagging, or excessive looping against underwater structures and currents.

4. Hazard Mitigation at Depth

• Delta P (Differential Pressure) Vigilance: Actively assess and respect potential closed or differential pressure hazards (pipes, valves, locks) that can create instant, catastrophic entrapment.
• Gas Buildup and Venting: When performing underwater burning or cutting (e.g., using a Broco torch), cut strategic vent holes to prevent pockets of explosive gasses from accumulating.
• Inert Gas Narcosis Recognition: Continuously self-monitor for cognitive slowing or behavioral changes associated with nitrogen or mixed-gas narcosis, communicating any anomalies immediately to the surface supervisor.

5. Controlled Ascent and Decompression

• Strict Decompression Tables: Adhere meticulously to approved decompression schedules and ascent rate limitations to promote safe inert gas elimination.
• Standby Diver and Chamber Readiness: Ensure a fully dressed standby diver is ready at the point of entry and that a recompression chamber is prepped and fully operational on-site before splashing.

If you are preparing for a specific operation, let me know:

• What is the target depth and mode of diving (surface-supplied air vs. mixed-gas/saturation)?
• What specific underwater task (welding, NDT, inspection) are you performing?

I can provide more targeted safety protocols or gear checklists.

For a commercial diver, deep diving should be treated as a team-controlled operation rather than something the diver manages alone. The exact procedures depend on depth, breathing gas, equipment, task, and whether the dive is surface-supplied or saturation, but these are core practices:

1. Follow a written dive plan

   • Establish maximum depth, bottom time, work scope, ascent/decompression profile, gas changes, and contingencies before entering the water.
   • Know the applicable decompression tables and maintain an accurate depth-time record throughout the dive. OSHA specifically requires a depth-time profile, including gas changes and decompression where applicable.

2. Never dive without an effective surface team

   • Maintain continuous communication with the surface.
   • Have a qualified supervisor and an immediately available standby diver appropriate to the operation.
   • Establish clear abort criteria before the dive. Loss of communications, failure to respond appropriately, or beginning to use reserve breathing gas are among OSHA's specified reasons to terminate a working dive.

3. Treat breathing-gas supply as mission-critical

   • Verify gas composition, purity, pressure, and quantity before going on-line.
   • Primary and independent backup supplies need sufficient capacity for the planned dive including decompression and emergencies.
   • Carry/use the required emergency breathing-gas system and know exactly how to switch to it.

4. Control decompression carefully

   • Deep dives can involve substantial inert-gas loading, decompression sickness, oxygen toxicity, nitrogen narcosis, and other pressure-related hazards.
   • Do not improvise an ascent or decompression schedule. Follow the schedule selected by the dive supervisor for the specific gas mixture and profile.
   • Report unusual symptoms immediately, including during the post-dive period.

5. Be particularly conservative about gas toxicity and narcosis

   • At depth, the partial pressures of oxygen and inert gases change substantially. Deep commercial operations may therefore require mixed gas rather than air, depending on the planned depth and procedure.
   • Don't alter gas mixtures, depth limits, or exposure times without authorization from the responsible diving supervisor.

6. Control entanglement, current, and work hazards

   • Keep the umbilical/lines managed and protected from propellers, machinery, structures, sharp edges, and pinch points.
   • Before energizing underwater tools, make sure the appropriate isolation and communication procedures have been completed. OSHA, for example, requires hand-held electrical equipment to be de-energized before entering or being retrieved from the water.
   • Treat Delta-P/suction hazards as potentially fatal and ensure they have been positively isolated before approaching them.

7. Know the emergency plan before descending The diver should know:

   • How to communicate an emergency.
   • How to obtain emergency breathing gas.
   • How the standby diver will reach them.
   • Where the decompression chamber is and how they will get there.
   • Who provides first aid/O₂ and how emergency transport will be activated.

   OSHA requires emergency communications and appropriate arrangements for treatment of diving-related medical emergencies; industry standards likewise emphasize trained surface personnel and emergency capability.

8. Monitor yourself continuously Don't try to "push through" confusion, unusual fatigue, breathing difficulty, chest pain, dizziness, ear/sinus problems, loss of coordination, or other abnormal symptoms. Tell the supervisor and terminate the dive when necessary. A diver's request to terminate is explicitly a reason to end the working interval under OSHA rules.

9. Don't let production pressure override safety Deep diving is especially unforgiving of shortcuts. If the gas supply, communications, decompression capability, equipment, weather/sea state, isolation, or personnel aren't adequate, the safe decision is to delay or abort the dive.

For U.S. commercial operations, the primary regulatory reference is OSHA 29 CFR Part 1910, Subpart T, supplemented by applicable maritime/construction requirements and the employer's dive manual. The ADCI International Consensus Standards are also widely used as commercial-diving best-practice guidance.

Bottom line: a safe deep dive depends on planned exposure + reliable breathing gas + continuous communications + competent surface support + controlled decompression + a rehearsed emergency plan. The diver should never be the only person responsible for making those safety decisions.

For a commercial deep dive, the most critical best practice to ensure personal safety is to strictly follow a comprehensive, pre-approved written dive plan and Job Safety Analysis (JSA) while maintaining continuous surface communication and monitoring of your dedicated gas umbilical and bailout cylinder . Unlike recreational diving, commercial deep operations involve heavy task loading, severe environmental pressures, and complex surface-supplied air or mixed-gas systems where individual survival depends heavily on absolute teamwork and procedural discipline.

Pre-Dive Planning and Gear Verification

• Conduct Tailgate Safety Meetings: Review the specific Job Safety Analysis with the entire surface crew and tender before entering the water to align on the work scope and emergency roles.
• Perform Rigorous Equipment Checks: Inspect your diving helmet, harness, communications, pneumofathometer, and ensure your independent bailout gas cylinder is fully pressurized, turned on, and functionally tested [0.28].
• Verify Surface Support Readiness: Confirm that the diving supervisor, surface tender, and standby diver are fully prepped and stationed at the control panel before leaving the surface.

Execution and Safety at Depth

• Maintain Constant Communication: Keep a continuous dialogue with your diving supervisor on the surface, using video feeds and audio lines to report task progress and physical status.
• Manage Gas and Narcosis Risks: Monitor your gas supply closely, account for increased gas density at depth, and remain vigilant for signs of nitrogen or mixed-gas narcosis that impair judgment.
• Control Task Loading: Avoid rushing or overexertion when operating heavy pneumatic or hydraulic tools; pause the operation immediately if visibility drops or structural hazards shift.

Ascent and Decompression Protocols

• Adhere to Decompression Schedules: Follow the exact, calculated ascent and in-water or chamber decompression profiles specified in your operational Safe Practices Manual.
• Monitor Umbilical and Depth: Prevent snagging or fouling of your umbilical line against subsea structures or debris during ascent.
• Execute Post-Dive Handoffs: Complete proper reporting and medical monitoring once back on the surface or inside the deck decompression chamber.

If you'd like, I can detail the specific emergency protocols for a fouled umbilical or outline the regulations set by the ADCI and OSHA for deep-water operations. Let me know how you'd like to proceed.

For a commercial diver, especially on a deep dive, personal safety starts with treating the dive as a team-controlled operation—not something the diver improvises underwater. OSHA notes that depth, bottom time, poor visibility, exertion, and construction hazards all compound the risks.

Key practices:

1. Dive within your training and authorization

   • Don't exceed the depth, gas, decompression, or equipment limits you've been trained and qualified for.
   • Deep mixed-gas and saturation operations require specialized procedures; don't substitute recreational-diving practices for commercial procedures.

2. Follow a written dive plan

   • Review depth, bottom time, work scope, gas supply, decompression schedule, environmental conditions, communications, and emergency procedures before entering the water.
   • Conduct a proper pre-dive briefing with the entire dive team and know exactly who is the designated person in charge.

3. Never dive without an effective surface team

   • For surface-supplied commercial diving, the diver should be continuously tended and have appropriate standby/rescue capability.
   • Maintain reliable communications with the surface whenever the diving system requires them.
   • Make sure the team knows the emergency signals and what to do if communications fail.

4. Protect your breathing-gas supply

   • Verify primary and secondary/reserve supplies before the dive.
   • Don't allow the job to consume your emergency reserve.
   • Surface-supplied systems need enough gas for the diver and required standby/decompression arrangements; U.S. maritime regulations specifically address primary and secondary supply requirements.
   • Be alert for changes in breathing resistance, gas quality, flow, or helmet/mask problems.

5. Treat decompression as a critical operation

   • Follow the prescribed decompression procedure exactly; don't shorten stops because you're cold, tired, behind schedule, or being pressured to finish.
   • Deep dives increase inert-gas loading, and decompression sickness can result when ascent/decompression doesn't adequately account for absorbed gas.
   • Never improvise a decompression schedule.

6. Control depth-related gas hazards

   • At depth, nitrogen narcosis can impair judgment and coordination, while inappropriate oxygen exposure can cause oxygen toxicity.
   • Use only the breathing mixture specified in the dive plan and verify gas identification and analysis before diving.

7. Manage entanglement and Delta-P hazards

   • Before starting work, identify intakes, discharges, pipelines, valves, pumps, electrical equipment, suspended loads, and other potential energy sources.
   • Ensure hazardous energy is isolated/locked out as required before entering the danger zone. OSHA specifically highlights Delta-P as a serious commercial-diving hazard.
   • Keep the umbilical routed and managed so it doesn't become an entanglement hazard.

8. Don't let the work itself compromise the dive

   • Avoid unnecessary exertion and monitor yourself for overheating, chilling, fatigue, breathing difficulty, confusion, or unusual symptoms.
   • If something feels wrong, stop work and tell the supervisor. Production pressure should never override a diver's safety concern.

9. Have a real emergency plan

   • Know what happens for loss of breathing gas, umbilical damage, lost communications, entanglement, loss of orientation, uncontrolled ascent/descent, contamination, fire, or medical emergency.
   • Know where the decompression/recompression capability is and how you will reach it. OSHA requires a chamber ready at the dive location for certain surface-supplied dives, including dives outside no-decompression limits or deeper than 100 fsw.

10. Inspect your equipment personally

    • Don't assume that because equipment was prepared by someone else it is ready for use.
    • Check helmet/mask, breathing system, umbilical, bailout/reserve, communications, depth indication, thermal protection, harness, and other job-specific equipment according to your company's procedures.

11. Know when to abort

    • Loss or degradation of breathing gas, communications, tending, visibility/orientation, thermal protection, or other critical controls can justify terminating the dive.
    • A diver should never continue simply because "the job is almost done."

For U.S. commercial operations, OSHA 29 CFR Part 1910 Subpart T is the regulatory baseline, while the ADCI International Consensus Standards provide widely used industry best practices.

Most important rule: on a deep commercial dive, don't rely on individual skill to compensate for a bad dive plan. The safest diver is one operating inside a properly planned, supervised, tended, gas-secure, decompression-controlled system with a practiced emergency response.