The fundamental rules of freediving safety

The first rule of freediving safety is to dive with a buddy, aka, never dive alone. Don't practice breath-holding alone in any body of water, including pools.

Hyperventilation has many undesirable physiological effects for freediving and greatly increases the risk of blackout. When getting ready for a dive, just focus on relaxation, both mental and physical.

Read more about the dangers of hyperventilation here.

A recovery breath consists of a quick exhale, a quick inhale, and a quick hold. Repeat this 3 times. Make it a habit even on easy dives, so that you have the muscle memory for it when you need it.

Read more about recovery breaths here.

A quick test of this is the "exhale test": if you exhale on the surface, do you sink or still float? If you sink, take off some weight. A more precise approach is to weight yourself so that you are positively buoyant at depths of 10 meters and above.

You can read more about how to weight yourself correctly here.

Sometimes in scuba diving it is appropriate to exhale while ascending. Exhaling can also very temporarily relieve the discomfort of carbon dioxide in the lungs. But your one breath contains precious oxygen, and also contributes to your buoyancy, so hold it until you return to the surface.

Your snorkel will prevent you from taking quick, full recovery breaths, and can also allow water into your mouth in the event of a blackout.

Just like in rockclimbing, attaching yourself to the line with a lanyard prevents you from falling away from it if you black out.

You can read more about how a lanyard helps keep you safe here.