Free diving is any of various aquatic activities that share the practice of breath-hold underwater diving. Examples include breathhold spear fishing, freedive photography, apnea competitions and, to a degree, snorkeling. The activity that garners the most public attention is competitive apnea, an extreme sport, in which competitors attempt to attain great depths, times or distances on a single breath without the assistance of self-contained underwater breathing apparatus (scuba).

Competitive freediving is currently governed by two world associations: AIDA International (International Association for Development of Apnea) and CMAS (World Underwater Federation). Most types of competitive freediving have in common that it is an individual sport based on the best individual achievement. All disciplines can be done by both men and women and, while done outdoors, no differences in the environment between records are recognized any longer. The disciplines of AIDA can be done both in competition and as a record attempt, with the exception of Variable Weight and No limits, which are both done solely as record attempts.

Pool disciplines consist of:

• Static Apnea is timed breath holding and is usually attempted in a pool (AIDA).
• Dynamic Apnea With Fins. This is underwater swimming in a pool for distance. For this discipline the athlete can choose whether to use bi-fins or the monofin (AIDA, CMAS).
• Dynamic Apnea Without Fins. This is underwater swimming in a pool for distance without any swimming aids like fins (AIDA).