The questions every freediver should ask first.

Yes — but it's rare and almost always linked to repeated deep dives with short surface intervals. A single recreational dive to 20–30 m carries negligible DCS risk. The risk rises sharply when you do many deep dives back-to-back, or when you go scuba diving and freediving on the same day. The standard rule: wait at least 12 hours after scuba before freediving deep, and 24 hours after deep freediving before flying. AIDA courses cover surface-interval guidelines for every depth range.

"The bends" is the same condition as decompression sickness. The mechanism in freediving is different from scuba — nitrogen accumulates from many short exposures rather than one long one — but the symptoms (joint pain, dizziness, neurological signs after surfacing) are similar. If you ever feel them, treat it as DCS, get out of the water, and seek hyperbaric care.

Shallow water blackout is a loss of consciousness caused by low oxygen, usually within the last few meters of an ascent or at the surface — exactly when divers feel they've made it. It happens because oxygen pressure drops as you ascend, and the urge to breathe (driven by CO₂) lags behind. It's the leading cause of death in freediving, and it's almost entirely preventable: never freedive alone, always have a trained buddy on the surface for the last 10 m and the first 30 seconds after surfacing, and don't push past your limits.

Done correctly, freediving has a strong safety record — comparable to other adventure sports. Done alone, without training, or while pushing breath-hold limits in a pool, it can kill you. The two non-negotiables: get certified through a real curriculum (AIDA or equivalent), and always dive with a trained buddy. Every fatal incident we know of broke at least one of these rules.

At shallow depths the Valsalva maneuver (the same one you use on a plane) works, but it stops being effective past about 15–20 m because it relies on your diaphragm — and the diaphragm locks up under pressure. Serious freedivers learn the Frenzel technique: using the tongue and throat to push air into the eustachian tubes, independently of the chest. Frenzel is taught in AIDA 2, refined in AIDA 3, and is the difference between stopping at 12 m and continuing to 30+ m.

AIDA 1 is one day and gets you breath-hold basics and a 10 m dive under supervision. AIDA 2, the first full certification, is three days and qualifies you to dive to 20 m with a buddy. Most people are diving safely and confidently within a week of structured instruction — but staying safe is a lifetime habit of small disciplines.