Free diving

Is freediving safe?

It can be, with one rule kept every time: someone trained must watch every dive. Freediving's main danger is a blackout from lack of oxygen, and blackouts are not rare events reserved for record attempts. In 38,789 AIDA competition dives in 2019–2023, divers lost consciousness 3.3% of the time. In competition, safety divers bring them up in seconds and they recover. Alone in the sea, the same blackout ends in drowning.

The best death rate we can build comes from New Zealand, where breath-hold diving mostly means gathering seafood such as crayfish and paua, or spearfishing. It works out at about 20 micromortsMicromortA one-in-a-million chance of death. It lets you compare the risk of very different activities on one scale.More in the glossary per diving trip, with a plausible range of 15 to 30. That is several times a scuba dive, at about 2 to 5 micromorts, though a freediving trip contains dozens of dives.

This page covers breath-hold diving: recreational and competitive freediving, spearfishing and diving for seafood. Floating on the surface with a snorkel is a different and lower-risk activity, though it appears in the same death statistics.

How many freedivers die per dive?

No study has published a death rate per freediving session, so we calculated one from two national counts. Lippmann and colleagues found 29 breath-hold divers who died gathering seafood in New Zealand in 2007–2016, about 2.9 a year. Fisheries New Zealand's national survey of recreational fishers estimated 123,442 trips in 2017–18 that involved gathering by diving and 33,969 that involved spearfishing. Some trips used both methods, so there were between about 123,000 and 157,000 diving trips.

Dividing 2.9 deaths by 157,000 trips gives about 18 per million; dividing by 123,000 gives about 23. The real figure could be lower, because the survey found about a quarter more fishing trips of all kinds in 2011–12, closer to the years of the deaths. It could be higher, because the survey's diving trips include some on scuba, and it asked but did not report how many. Our range of 15 to 30 covers both.

Australia gives a rough check. About 88,000 Australians aged 15 and over snorkel or breath-hold dive in a year, by the Australian Sports Commission's estimate, and about 8 Australian residents a year died doing so in 2000–2021. That is about 9 deaths per 100,000 participants a year, with surface snorkellers included. For overseas visitors snorkelling in Queensland, mostly on the surface, the published rate for 2005–2019 was 1.25 deaths per 100,000 snorkellers a year.

Why freedivers die

The pattern in the case series is consistent. In Australia, Lippmann and colleagues reviewed 317 snorkelling and breath-hold deaths from 2000 to 2021. Two groups stood out:

• Younger, fit, experienced breath-hold divers, median age 35, who drowned after blacking out. Up to 34 deaths followed apnoeic hypoxia, the medical term for running out of oxygen while holding your breath. Eight of those happened in swimming pools, where people practised long breath-holds with nobody closely watching.
• Older surface snorkellers, median age 58, often overweight, with heart disease that had not always been diagnosed. Immersion, cold and effort load the heart.

Spearfishing accounted for 20% of the Australian deaths and seafood harvesting another 11%. New Zealand's deaths look different: mostly middle-aged men gathering seafood in shallow water (a median of 3 metres where depth was recorded), with heart problems involved in 18 of 38 deaths. About two-thirds were alone or not being watched.

DAN's earliest review of its breath-hold cases, covering 1994–2004, found 98% of the 145 reports involved a death, and named excessive hyperventilation before a dive, leading to shallow water blackout, as a likely major factor.

The blackout problem

Blackout during a breath-hold is sudden. Oxygen falls steadily during the dive, and on ascent the drop in water pressure makes it fall faster, so many blackouts happen in the last few metres or just after surfacing. There is usually no warning the diver can feel.

Spearfishing makes it worse. A spearfisher focused on a fish stays down longer, dives again and again with short rests, and often hunts apart from a buddy to avoid scaring the fish. Each dive is a small gamble, and a session may involve dozens.

The competition data show what pushes risk up. Blackout rates were highest in the disciplines without fins, about 1.5 times the risk of other disciplines in the pool and 2 times at depth. Lung squeeze (pulmonary barotrauma), where the chest is compressed at depth and the lungs bleed, happened in 0.4% of dives.

Who should be careful

• Spearfishers and seafood gatherers. They make up most of the breath-hold deaths in New Zealand and a third in Australia.
• Anyone practising breath-holds alone, including in a pool or bath. Static breath-hold training should always be done with a person watching from close by.
• Older divers and snorkellers with heart risk factors. Talk to your doctor before snorkelling or diving if you have heart disease, high blood pressure, diabetes or a history of fainting.
• Divers pushing depth without a line and safety team. Deep dives need a fixed line, a lanyard and a safety diver who meets you on the way up.

How to freedive more safely

1. One up, one down. Your buddy stays on the surface and watches your whole dive, then watches you for at least 30 seconds after you surface. Then you swap.
2. Never hyperventilate. Breathe calmly before a dive. Hyperventilation delays the urge to breathe, not the blackout.
3. Take a course. Freediving agencies teach rescue of a blacked-out diver, which is the skill that saves lives.
4. Rest between dives, at least twice as long as the dive itself, longer after deep dives.
5. Stay well inside your limits when spearfishing, and never chase a fish past your planned bottom time.
6. Ditch weight at the surface. Weight yourself so you float at the surface and can release your belt quickly.

How we scored it

Fatality risk (55) rests on about 20 micromortsMicromortA one-in-a-million chance of death. It lets you compare the risk of very different activities on one scale.More in the glossary per trip: 2.9 deaths a year among New Zealand's breath-hold seafood divers (2007–2016) divided by 123,000 to 157,000 diving trips (2017–18), with a range of 15 to 30. Confidence is medium, not high: the two counts come from different years, the trips include some scuba dives and the figure covers one country's seafood divers, not deep or competitive freediving. Injury risk (65) reflects frequent blackouts and lung squeezes, controllability (72) a watching buddy who turns most blackouts into a scare, and the open-water environment (45) scores poorly. For a sport where an overhead environment adds more risk, see cave diving.