Recognise decompression illness (DCS and arterial gas embolism)
â
Do
- Suspect DCS with joint or muscle pain, numbness or tingling, weakness or paralysis, unusual fatigue, itchy or blotchy skin, dizziness, ringing in the ears, shortness of breath, bladder difficulty, confusion or staggering after a dive.
- Remember DCS symptoms usually appear within 15 minutes to 12 hours after surfacing, and mild cases are often wrongly blamed on overexertion or a tight wetsuit.
- Treat any suspected DCI as real until a diving-medicine physician says otherwise, even if symptoms seem to resolve.
â Don't
- Don't dismiss symptoms that improve on oxygen â DAN reports symptoms returning hours later.
- Don't attempt in-water recompression. Take a symptomatic diver out of the water and give first aid at the surface.
- Don't re-dive to 'treat' symptoms or to finish the dive plan.
When to call: Any suspected DCS or AGE: call local emergency services, then a dive emergency hotline (e.g. DAN +1-919-684-9111) â even if symptoms have resolved.
Source: Decompression Illness: What Is It and What Is the Treatment? · checked 2026-10-17 · Source: Dive Medical Reference: Treating Decompression Sickness · checked 2026-10-17
Arterial gas embolism (AGE) is a time-critical emergency
â
Do
- Suspect AGE with dizziness, blurred vision, chest pain, disorientation, bloody froth from mouth or nose, weakness, convulsions or unconsciousness soon after surfacing.
- Treat loss of consciousness within about 10 minutes of surfacing as a medical emergency needing rapid evacuation.
- Start CPR if the diver is not breathing normally; give the highest concentration of oxygen available.
- If the diver vomits, turn them on their side to keep the airway clear.
â Don't
- Don't delay evacuation to collect information.
- Don't attempt in-water recompression.
When to call: Immediately: local emergency services first, then a dive emergency hotline.
Source: Decompression Illness: What Is It and What Is the Treatment? · checked 2026-10-17 · Source: Dive Medical Reference: Treating Decompression Sickness · checked 2026-10-17
Emergency oxygen first aid
â
Do
- Give oxygen as early as possible â DAN calls oxygen the primary first aid for DCS and AGE.
- Aim for 100% oxygen / the highest concentration practical, with a good mask fit and an appropriate flow rate.
- Use a demand-type mask only for a conscious diver who is breathing on their own.
- Continue oxygen until medical professionals take over.
- For a non-breathing diver, DAN describes an oronasal resuscitation mask with oxygen; oxygen must not delay CPR.
â Don't
- Don't let oxygen first aid change the plan to get the diver to definitive (hyperbaric) medical care â symptoms can return after seeming to resolve.
- Don't delay CPR or other lifesaving care to set up oxygen.
When to call: Start oxygen and call emergency services at the same time; then call a dive emergency hotline for advice on next steps.
Source: Dive Medical Reference: Treating Decompression Sickness · checked 2026-10-17 · Source: Alert Diver: Oxygen · checked 2026-10-17 · Source: Decompression Illness: What Is It and What Is the Treatment? · checked 2026-10-17 · Source: Travelers Medical Guide 6.2: Rescuing Divers and Swimmers · checked 2026-10-17
Caring for an injured diver while help is on the way
â
Do
- Position per DAN: a responsive diver in the recovery position (on one side, head supported) or reclined in whatever position is comfortable; an unresponsive diver who is breathing in the recovery position to keep the airway open; an unresponsive diver who is not breathing flat on their back (supine) for CPR. Turn to the side if they vomit.
- Keep the diver warm â prevent further heat loss (DAN, hypothermia care) â and handle gently.
- Give fluids by mouth only if the diver is fully conscious and able to swallow (DAN lists oral fluids for urgent, conscious cases).
- Record the dive profile(s) and the previous dives, time symptoms started, first aid given and any changes; keep the dive computer with the diver.
- Secure the injured diver's gear exactly as it was when removed: do not close the cylinder valve, adjust or disassemble it, and release it only to law enforcement/investigators.
- Do a simple neurological check if possible, without delaying evacuation.
â Don't
- Don't give painkillers unless advised by medical personnel.
- Don't fly or travel to altitude after a suspected DCI without diving-medicine advice â altitude exposure increases DCS risk.
- Don't put a symptomatic diver back in the water (no in-water recompression).
When to call: Call local EMS first, then DAN / the dive emergency hotline, as soon as DCI is suspected; ask the hotline physician before any flight.
Source: Decompression Illness: What Is It and What Is the Treatment? · checked 2026-10-17 · Source: Dive Medical Reference: Treating Decompression Sickness · checked 2026-10-17 · Source: Travelers Medical Guide 6.2: Rescuing Divers and Swimmers · checked 2026-10-17 · Source: Travelers Medical Guide 5.1: Exposure-Related Injuries · checked 2026-10-17 · Source: DAN RRG Incident Aftermath Information 2025/2026 (PDF) · checked 2026-10-17
CPR for a non-breathing diver after drowning or submersion (adult)
â
Do
- Get the diver out of the water onto a firm, flat surface and lay them on their back â CPR in the water is ineffective (DAN).
- If unresponsive and not breathing normally, call emergency services (or have someone call) and send for an AED and oxygen.
- Open the airway and give 5 initial rescue breaths (mouth-to-mouth or mouth-to-nose, or with 100% oxygen through a mask/bag if available and trained) â in drowning the arrest is usually caused by lack of oxygen (ERC 2021).
- If the diver is still unresponsive and not breathing normally, start chest compressions: 30 compressions, then 2 rescue breaths, and repeat (30:2).
- Attach an AED as soon as one is available and follow its prompts.
â Don't
- Don't start with compressions only for a drowning victim if you are able to give rescue breaths â breaths come first.
- Don't attempt CPR in the water; start breaths and compressions once the diver is on a stable surface (trained rescuers may begin breaths in the water or compressions on a boat, per ERC).
- Don't interrupt chest compressions for more than 10 seconds once started.
When to call: Immediately when a person is unresponsive and not breathing normally; then a dive emergency hotline.
Source: ERC Guidelines 2021: Cardiac arrest in special circumstances, section Drowning (Lott C et al., Resuscitation 2021;161:152-219) · checked 2026-10-17 · Source: Kreislaufstillstand unter besonderen UmstÀnden, Abschnitt Ertrinken (official German edition of the ERC Guidelines 2021, Notfall + Rettungsmedizin 2021, doi:10.1007/s10049-021-00891-z) · checked 2026-10-17 · Source: Travelers Medical Guide 6.2: Rescuing Divers and Swimmers · checked 2026-10-17
CPR basics for a non-breathing adult (cardiac arrest, not drowning)
â
Do
- Place the person on their back on a firm, flat surface.
- If unresponsive and not breathing or only gasping, call emergency services (or have someone call) and get equipment (AED).
- Give chest compressions: two hands centred on the chest, at least 2 inches (5 cm) deep, 100â120 per minute, 30 at a time, letting the chest recoil.
- Give 2 rescue breaths (about 1 second each, making the chest rise) after each 30 compressions.
- Continue sets of 30 compressions and 2 breaths; use an AED as soon as one is available.
- If the person was pulled from the water (drowning or submersion), use the drowning sequence instead: 5 initial rescue breaths first.
â Don't
- Don't interrupt chest compressions for more than 10 seconds.
- Don't spend more than 10 seconds checking for breathing.
When to call: Immediately when a person is unresponsive and not breathing normally.
Source: CPR Steps · checked 2026-10-17 · Source: ERC Guidelines 2021: Cardiac arrest in special circumstances, section Drowning (Lott C et al., Resuscitation 2021;161:152-219) · checked 2026-10-17
Missing or lost diver
â
Do
- At sea, raise the alarm at once: call the Coastguard on DSC / VHF channel 16 or dial the national emergency number (UK: 999, ask for the Coastguard).
- Give the Coastguard your position (preferably latitude and longitude), the nature of the emergency, the assistance required and the number of persons involved â the same content as a distress message.
- If the situation is not (yet) grave and imminent danger, an urgency (PAN PAN) call may be appropriate; escalate to MAYDAY if a life is in danger.
â Don't
- Don't delay raising the alarm.
When to call: As soon as a diver is overdue or unaccounted for.
Source: In the event of a diving incident · checked 2026-10-17 · Source: GMDSS VHF DSC procedures for small boat users · checked 2026-10-17 · Source: Radio Aids to Marine Navigation 2026: Part 4 General · checked 2026-10-17
Commercial: standby diver readiness and deployment
â
Do
- Have a standby diver in immediate readiness whenever a diver is in the water â HSE L103 advises one standby for every two divers in the water.
- Keep the standby dressed to enter the water, with mask or helmet immediately to hand; for surface-supplied diving the standby remains on the surface (or inside a closed bell when deployed from one).
- Plan the minimum team (HSE L103 normally five for surface-supplied offshore: supervisor, working diver, standby diver, and a tender for each).
- Make sure the diving project plan includes contingency procedures for foreseeable emergencies, including retrieving injured and unconscious divers from the water.
â Don't
- Don't assign the standby duties that would stop them deploying immediately.
- Don't begin diving if the contingency and emergency plans have not been briefed to the team.
When to call: Supervisor deploys the standby on any diver emergency (loss of comms, entrapment, gas loss, unconsciousness) and activates the project emergency plan.
Source: L103 Commercial diving projects offshore (Diving at Work Regulations 1997 ACOP) · checked 2026-10-17 · Source: Diving Approved Codes of Practice · checked 2026-10-17 · Source: IMCA D014 International code of practice for offshore diving (Rev. 3.3, March 2025) · checked 2026-10-17
Commercial: communications and loss of communications
â
Do
- Every diver in the water needs direct voice communication with the surface supervisor (helium speech unscrambler where heliox is breathed).
- Record diver communications and keep the recording at least 48 hours after the diver returns; keep it longer if an incident occurs.
- State the working language in the diving project plan â people revert to their native language in emergencies.
- Treat loss of voice communication as an emergency per the project contingency plan (e.g. terminate the dive and prepare the standby).
â Don't
- Don't continue working with lost or unreliable diver communications.
When to call: Activate the contingency procedure immediately on loss of comms; escalate per the project emergency plan.
Source: L103 Commercial diving projects offshore (Diving at Work Regulations 1997 ACOP) · checked 2026-10-17
Commercial: emergency gas and entrapment
â
Do
- Calculate gas quantities (primary, secondary and therapeutic) with allowances for leakage, wastage and contingencies; stop diving if gas falls below the agreed minimum.
- Ensure each diver has an emergency gas supply and that emergency breathing gas cylinders are in a standard layout in any diving basket.
- Examine and maintain emergency gas cylinders regularly (accelerated corrosion risk).
- Plan for entrapment and for retrieval of an injured or unconscious diver in the contingency procedures.
â Don't
- Don't dive without a planned, checked emergency gas supply.
When to call: On any gas supply failure or entrapment, deploy the standby and follow the emergency plan.
Source: L103 Commercial diving projects offshore (Diving at Work Regulations 1997 ACOP) · checked 2026-10-17 · Source: IMCA D014 International code of practice for offshore diving (Rev. 3.3, March 2025) · checked 2026-10-17
Commercial: hyperbaric evacuation and chamber medical planning (concept)
â
Do
- For saturation diving, plan hyperbaric evacuation: divers in saturation cannot leave by normal routes and must be evacuated under pressure (e.g. hyperbaric rescue chamber or lifeboat) with life support for at least 72 hours (HSE L103).
- Include emergency response and contingency plans and hyperbaric evacuation arrangements per IMCA D014 and related IMCA guidance.
- Prepare contingency plans, with the company medical adviser, for a diver who becomes seriously ill or injured while under pressure.
- Arrange in advance how site personnel will reach the diving contractor's medical adviser by radio/telephone and how information is passed to a doctor.
â Don't
- Don't start saturation operations without a tested hyperbaric evacuation plan.
When to call: Activate the hyperbaric evacuation plan as soon as the worksite becomes untenable.
Source: L103 Commercial diving projects offshore (Diving at Work Regulations 1997 ACOP) · checked 2026-10-17 · Source: IMCA D014 International code of practice for offshore diving (Rev. 3.3, March 2025) · checked 2026-10-17
Before every dive: emergency readiness
â
Do
- Know the local emergency number and the dive emergency hotline for the area; save them in the dive plan.
- Have emergency oxygen available â DAN calls it the primary first aid for DCS and AGE.
- Know how to call the Coastguard on VHF channel 16 / DSC.
- Confirm, by phone, the nearest available recompression facility â and never go there without contacting them first.
â Don't
- Don't rely on a chamber listing alone; availability changes.
When to call: In any emergency: local emergency services first, then the dive emergency hotline.
Source: Emergency Assistance · checked 2026-10-17 · Source: Emergency · checked 2026-10-17 · Source: In the event of a diving incident · checked 2026-10-17 · Source: Dive Medical Reference: Treating Decompression Sickness · checked 2026-10-17 · Source: GMDSS VHF DSC procedures for small boat users · checked 2026-10-17
