When free diving, the diver fills his lungs with air which he inhales on the surface, while underwater he stops breathing. Naturally, the length of the dive underwater is limited and cannot surpass the length of time the diver can hold his breath. During diving, the free diver's lungs are affected by the rise of the environmental pressure. When going deeper, the air pressure in his lungs equalizes to the environmental pressure, which is why the chest shrinks. The deeper the diver goes, then, the more his lungs are compressed and the air pressure within them grows. When ascending, the diver's lungs widen and return to their normal size. At the same time, the air pressure within them grows smaller. On top of this, the pressure directly affects the middle ear. Because of this, the diver must equalize the pressure in his ears by pumping. Free diving is limited within the aspects of depth and duration of time the diver can remain underwater, unless we are talking about a professional diver, with lots of training and much experience.

• Dive with a dive buddy (one dives and the other remains above water).
• It is advisable to equip oneself with a life vest and rest between dives.
• You must equalize pressure in your ears and stop descending if you cannot do this.
• Dive with your lungs full of air.
• Do not hyper-ventilate before holding your breath.
• Even when free diving, use a buoy with a dive flag.
• It is recommended to wear a shirt to avoid getting sunburned.