Freediving is an activity in which a person dives, sometimes to great depth, without the use of scuba gear. the diver must hold his or her breath for the duration of the dive. (the record depth, with no equipment such as diving fins, is 101 m; the official record time is over 11 minutes.) historically, freediving has been used by pearl divers and sponge divers. some freedivers hyperventilate (breathe rapidly and deeply) before diving. hyperventilation can change the concentration of co2 in the blood and may inc