Rescue principles for a blacked-out diver
Explainer · Last reviewed 2026-08-27
The buddy system only works if the person watching knows what to do in the seconds after they see it — and this is the one subject in the discipline where reading is explicitly not enough.
Safety: shallow water blackout and breath-hold loss of consciousness — can cause serious injury or death.
Never dive alone, dive one up one down, and never extend a dive for a fish.
Shallow water blackout and breath-hold loss of consciousness — Can cause serious injury or death
A diver loses consciousness without warning, most often in the final part of the ascent or in the seconds after surfacing. It is silent, there is no struggle, and survival depends almost entirely on somebody competent being in position to get the airway clear of the water immediately.
What reduces it: Recognised freediving or spearfishing training that includes assessed in-water rescue, practised periodically; one-up-one-down with the supervising diver observing the whole dive and the thirty seconds after surfacing; shallower and shorter dives when visibility prevents observation; and diving well inside the margin rather than near it.
Every safety page in this vertical ends at the same place: somebody competent is watching. This is the page about what that person does, and it opens with the thing that has to be said first.
THIS CANNOT BE LEARNED FROM READING. Rescue is a physical skill performed under time pressure on an unresponsive person in water, and it is taught and assessed in the water on every recognised freediving and spearfishing course. FishingHQ describes the principles so that a diver understands what their buddy is for and can recognise a course that teaches it properly. It is not a substitute for the course, and anybody diving without that training should understand that their buddy arrangement is incomplete.
WHAT A BLACKOUT LOOKS LIKE. A diver who stops swimming, or whose movement becomes uncoordinated, or who releases a large mass of bubbles from the mouth — which is a recognised sign. It happens most often during the final part of the ascent, where the drop in ambient pressure is steepest, or at the surface in the moments after breathing has resumed. It is silent. There is no struggle and no call for help.
THE PRINCIPLES, IN ORDER.
GET THEM TO THE SURFACE. Everything else waits.
GET THE AIRWAY OUT OF THE WATER AND KEEP IT THERE. This is the whole of the immediate priority — the mouth and nose clear, and the face supported.
REMOVE THE MASK AND ANY WEIGHT that is preventing flotation.
STIMULATE AND TALK TO THEM. Many blackouts resolve within seconds once the airway is clear and breathing resumes; the recognised approach is to prompt the diver rather than to begin doing things to them.
CALL FOR HELP EARLY rather than after deciding it is serious.
IF BREATHING DOES NOT RESUME, this is a drowning emergency and the response is the standard one for an unresponsive casualty, which is again a taught skill rather than a described one.
AND AFTERWARDS: THE SESSION IS OVER. For both divers. A diver who has blacked out does not go back in that day, regardless of how quickly they recovered and regardless of how well they feel, and they should be assessed medically.
Why the buddy has to be close, and what close means
The rescue principles decide the buddy protocol rather than the other way round, and this is where one-up-one-down stops being a slogan.
TIME IS THE CONSTRAINT. A diver who blacks out underwater needs to reach the surface with their airway clear, and the person doing that has to be in a position to intervene. Watching from thirty metres away, or from the beach, or while looking at your own fish, is not the same activity.
SO THE PRACTICAL STANDARD is a buddy who is at the surface, in position, and actually observing the diver through the whole of the dive — including the ascent, which is when it is most likely to happen, and including the thirty seconds after surfacing, which is the other window.
VISIBILITY CHANGES WHAT THAT REQUIRES. In clear water a buddy can watch from the surface. In three metres of visibility they cannot, which means shallower dives, shorter dives, and being closer — the point made in the conditions family and repeated here because this is where the consequence lands.
ALTERNATING PROPERLY. One diver down, one watching, and swapping. Two divers descending together is two people unsupervised, and it is the commonest way an experienced pair ends up with nobody watching.
AND THE HONEST LIMIT. A buddy who is not trained in rescue is better than no buddy — they can raise the alarm and get somebody to the surface — and they are not what the safety model assumes. The gap between those two is the reason training comes first in this vertical rather than second.
Official guidance — why, and the sources (3)
Stated by a fisheries authority, scientific institute or recognised angling body. Authoritative, but summarising rather than demonstrating.
- DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: That blackout occurs most often during the final stage of ascent or shortly after surfacing, that a large release of bubbles is a recognised sign, and that dedicated one-to-one buddy supervision is required.States this directlyPassage read and verified
- BSAC diving safety guidance and annual incident report — British Sub-Aqua Club (Water-safety or diver-training authority)Relied on for: Buddy protocol, separation and the requirement for the supervising diver to observe throughout.States this directlyCitation checked — the work exists and is described correctly
- AIDA International freediving education and safety standards — AIDA International (Water-safety or diver-training authority)Relied on for: That rescue procedure is a taught and assessed component of recognised freediving education standards.States this directlyCitation checked — the work exists and is described correctly
What FishingHQ will not publish here
This page deliberately stops short of a procedure.
NO STEP-BY-STEP RESCUE SEQUENCE, no timings, no rescue-breath technique, and no description detailed enough to be mistaken for training. Somebody who has practised a rescue in the water needs none of it, and somebody who has not would be worse off attempting a half-remembered sequence than calling for help and getting the airway clear.
NO ADVICE ON DIVING WITHOUT A TRAINED BUDDY, in any form, including advice about how to make it safer. There is no version of this activity that FishingHQ describes as acceptable alone, and framing risk reduction for solo diving would be exactly that description.
NO PERFORMANCE CONTEXT. Blackout risk rises with breath-hold duration and depth, and this platform publishes nothing that would help a diver extend either. Where the two subjects touch, the answer is always to dive further inside the margin rather than to manage a smaller one.
WHAT TO DO INSTEAD. Take a recognised freediving or spearfishing course that includes in-water rescue, practise it periodically rather than once, and dive with somebody who has done the same. That is the whole recommendation, and it is the one intervention that reliably changes what happens on a bad day.
Official guidance — why, and the sources (1)
Stated by a fisheries authority, scientific institute or recognised angling body. Authoritative, but summarising rather than demonstrating.
- AIDA International freediving education and safety standards — AIDA International (Water-safety or diver-training authority)Relied on for: The existence of structured, assessed freediving education including in-water supervision and rescue.States this directlyCitation checked — the work exists and is described correctly
Safety
Shallow water blackout and breath-hold loss of consciousness is set out at the top of this page, where it cannot be missed.
Never dive alone, dive one up one down, and never extend a dive for a fish. The full set of breath-hold essentials — training, the buddy system, conditions, equipment and visibility — is on the spearfishing safety page.
Further safety reading
- Breath-hold blackout — Blackout is silent, gives no warning, and happens most often on the final part of the ascent or just after surfacing.
- The spearfishing buddy system — The rescue principles decide the buddy protocol rather than the other way round, which is where one-up-one-down stops being a slogan.
- Training and courses — In-water rescue is taught and assessed on recognised courses, and a buddy who has not done one is not what the safety model assumes.
Where to go next
Where it matters
More explainers
Not related to this page — just the rest of the section. There is little else joined to this subject yet, and a short page should still lead somewhere.
Sources and evidence
- DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Blackout mechanism, timing, recognition signs and the requirement for supervision.States this directlyPassage read and verified
- BSAC diving safety guidance and annual incident report — British Sub-Aqua Club (Water-safety or diver-training authority)Relied on for: Buddy protocol and diving incident response.States this directlyCitation checked — the work exists and is described correctly
Why the 5 connections on this page are here, and the sources
Where it matters
Official guidance — 2 connections
Stated by a fisheries authority, scientific institute or recognised angling body. Authoritative, but summarising rather than demonstrating.
Freediving for spearfishing
A membership assertion rather than a topical one: this page teaches the discipline or its equipment, so the discipline's mandatory safety posture applies to it.
- DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Freediving and breath-hold spearfishing safety practice, including the supervision requirement that applies across the discipline rather than to particular equipment.States this directlyPassage read and verified
- CMAS technical and sporting standards for underwater activities — Confédération Mondiale des Activités Subaquatiques (Standards body)Relied on for: Breath-hold diving safety practice and discipline definition set out by the international underwater federation.States this directlyCitation checked — the work exists and is described correctly
Spearfishing
The one subject in this vertical where reading is explicitly not enough, said so on the page.
- DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Diving medicine guidance on breath-hold physiology, hypoxic blackout, cold exposure and supervision.States this directlyPassage read and verified
Safety reading
Official guidance — 3 connections
Stated by a fisheries authority, scientific institute or recognised angling body. Authoritative, but summarising rather than demonstrating.
Breath-hold blackout
The mechanism the rescue exists to answer.
- DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Diving medicine guidance on breath-hold physiology, hypoxic blackout, cold exposure and supervision.States this directlyPassage read and verified
The spearfishing buddy system
Why the buddy has to be close, derived rather than asserted.
- DAN guidance on freediving safety, hypoxia and shallow-water blackout — Divers Alert Network (Water-safety or diver-training authority)Relied on for: Diving medicine guidance on breath-hold physiology, hypoxic blackout, cold exposure and supervision.States this directlyPassage read and verified
Training and courses
The intervention this page ends by recommending, and the only one that reliably changes the outcome.
- AIDA International freediving education and safety standards — AIDA International (Water-safety or diver-training authority)Relied on for: That recognised freediving education is structured and assessed, and includes in-water rescue.States this directlyCitation checked — the work exists and is described correctly
How FishingHQ labels evidence is explained in the evidence policy.