Decompression Illness and Freediving: What Divers Need to Know

Decompression problems are reported far less often in freediving than in scuba, but deep, repetitive breath-hold diving is not risk-free.

Updated September 2026

Most recreational freedivers will never experience decompression illness. However, documented cases show that neurological injury can occur—particularly after deep or highly repetitive dives, short surface intervals, long sessions or extreme single dives. The safest response is to understand the limits of the evidence, use conservative dive planning and treat possible symptoms as a medical emergency.

Rare does not mean impossible The true incidence is unknown, but both decompression sickness and arterial gas embolism have been reported after breath-hold diving.

Repetition matters Repeated dives, short recoveries, greater depth and long diving sessions are the patterns most consistently associated with risk.

Symptoms need urgent action Stop diving, provide emergency oxygen if trained, call Triple Zero and contact the DAN diving emergency service.

DCS, AGE and the broader term “DCI”

Decompression illness (DCI) is the broader term used for injury associated with gas bubbles after a reduction in pressure. It includes decompression sickness (DCS), where dissolved inert gas forms bubbles in tissues or blood, and arterial gas embolism (AGE), where gas enters the arterial circulation.

This distinction matters because the post-dive neurological injuries reported in breath-hold divers may involve DCS, AGE or overlapping mechanisms. A diver should not try to decide which one is occurring at the dive site—the first-aid response is urgent regardless.

“Taravana” is not a harmless freediving buzzword

The term was historically used for neurological illness in people making many deep breath-hold dives with short surface intervals. Modern reports describe dizziness, visual changes, weakness, speech difficulty, confusion and brain injury.

How can decompression illness occur on one breath?

Dry air is roughly 78% nitrogen. Even at the surface, body tissues contain dissolved nitrogen in equilibrium with the air we breathe. During descent, increasing pressure compresses the gas in a freediver’s lungs and raises its nitrogen partial pressure. Some nitrogen can move from the lungs into blood and tissues.

A breath-hold diver does not keep breathing compressed gas at depth, so inert-gas exposure is usually far lower than during scuba. That is why DCI is much less commonly reported in ordinary freediving. The exposure can become more important when dives are deep, long or repeated before the nitrogen from earlier dives has been sufficiently cleared.

During ascent, ambient pressure falls. If tissues become sufficiently supersaturated, bubbles may form or contribute to vascular injury. The precise mechanisms in breath-hold divers are still being studied, and neurological events may also involve arterial gas embolism.

Important correction: deliberately slowing a freediver’s ascent is not a proven decompression strategy. A slow ascent increases breath-hold time and can worsen hypoxia. Do not add improvised decompression stops or alter your ascent technique unless you are following a specialist protocol under qualified supervision.

Profiles associated with greater concern

Many repetitive dives

Frequent descent-and-ascent cycles can allow residual nitrogen to build across a session, especially when the surface recovery is short.

Greater depth or duration

Deeper dives raise nitrogen partial pressure, while longer exposure gives more time for gas transfer. A few cases have followed exceptionally deep single dives.

Long diving shifts

Occupational and spearfishing cases often involve hours of repetitive diving rather than one ordinary recreational session.

Freediving after scuba

Scuba can leave significant residual inert gas. Repeated pressure cycling during subsequent freedives may add risk, particularly when the freedives are deep.

Surface intervals: why one formula is not enough

The former version of this article gave rigid formulas based on dive time and depth. Those calculations are used in parts of the freediving community, but current evidence does not establish one universal formula that guarantees protection from DCI.

A suitable recovery depends on the complete profile: depth, duration, number of dives, total session length, previous compressed-gas exposure and the diver’s condition. Increase surface time as dives become deeper, longer or more repetitive, and follow the procedures taught by your recognised freediving agency and instructor.

If your session involves deep line diving, repetitive spearfishing, assisted propulsion, safety diving or multiple days of demanding profiles, use a plan developed for that activity rather than a generic internet rule.

Possible warning signs after freediving

Breath-hold diving injuries can resemble other medical problems, and not every symptom is DCI. Do not dismiss an unusual symptom simply because the dive was completed on one breath or seemed shallow.

Dizziness, vertigo or loss of balance
Blurred or double vision
Numbness, tingling or unusual weakness
Difficulty speaking, understanding or walking
Confusion, unusual behaviour or severe fatigue
Loss of consciousness or seizure
Chest pain, breathing difficulty or coughing blood
Persistent or worsening symptoms after surfacing

Chest or breathing symptoms may indicate lung squeeze, pulmonary oedema or another serious condition rather than DCS. The correct action is still to stop diving and obtain urgent medical assessment.

What to do if decompression illness is suspected

Stop diving immediately and bring the diver safely out of the water.
Call Triple Zero (000) for serious, neurological, breathing or worsening symptoms. Do not delay emergency care while trying to identify the exact injury.
Give the highest available concentration of oxygen using appropriate equipment if a trained provider is present. Monitor breathing and be ready to begin CPR if required.
Contact the DAN diving emergency hotline within Australia on 1800 088 200 for specialist diving-medicine assistance. This complements—not replaces—calling emergency services.
Do not attempt in-water recompression, return to depth or fly. Keep the diver at rest and follow the directions of emergency and diving-medicine professionals.

Practical ways to reduce risk

Train with a recognised freediving instructor. Learn appropriate progression, buddy procedures, rescue skills and recovery intervals for the activity.
Reduce exposure. Limit depth, duration, repetitions and total session length instead of relying on one “safe” number.
Allow generous surface recovery. Extend it as the session becomes deeper or more repetitive, and stop rather than compressing recovery time.
Plan scuba and freediving conservatively. Freedive first where practical, or separate the activities and follow qualified guidance.
Stay warm, hydrated and well. These support general diving safety but do not make an aggressive profile safe or eliminate DCI risk.
Never freedive alone. A trained, attentive buddy remains essential because hypoxic loss of motor control, blackout and drowning are more immediate hazards than DCI for most recreational freedivers.
Stop for unusual symptoms. Do not “test” whether dizziness, visual disturbance, weakness or breathing difficulty will disappear on another dive.

Common questions

Is decompression sickness impossible in freediving?

No. It is reported far less often than in compressed-gas diving, but documented cases show that DCI can follow repetitive, deep or extreme breath-hold profiles.

Is a three-times-the-dive-time surface interval guaranteed to be safe?

No formula guarantees safety for every profile or diver. Follow the procedures taught by your agency and instructor, allow longer recovery as exposure increases and use specialist planning for demanding sessions.

Should I ascend slowly to avoid DCS?

Do not deliberately slow your ascent as an improvised decompression method. Extending the breath-hold can increase hypoxia. Use the ascent technique taught for your discipline and reduce the planned exposure instead.

Can I freedive after scuba if I wait 12 hours?

There is no single interval that fits every scuba exposure and planned freedive. A conservative approach is to freedive before scuba or on a separate day, following the most cautious applicable advice from your agency, operator or diving doctor.

Does feeling better mean the emergency has passed?

No. Neurological symptoms may be mild, fluctuate or temporarily improve. Stop diving and seek urgent diving-medical advice even if the symptom appears to resolve.

Research and emergency information

This article provides general safety information, not individual medical advice or a decompression procedure. Diving profiles and symptoms should be assessed by appropriately qualified diving professionals and medical practitioners.

Learn freediving physiology and safety properly

A structured course teaches breath-hold physiology, safe progression, direct buddy supervision, rescue procedures and the practical limits that cannot be learned responsibly from a depth formula alone.

View the PADI Freediver course Review the diver medical questionnaire