I love swimming in the ocean especially deep sea diving or underwater diving.
Interesting, particularly because humans are not exactly built for the environmental conditions of diving! 
Yeah. The professional free divers can hold their breaths for 5 minutes and longer I think.
diver is directly exposed to the pressure of the surrounding water. The ambient pressure diver may dive on breath-hold, or use breathing apparatus for scuba diving or surface-supplied diving, and the saturation diving technique reduces the risk of decompression sickness (DCS) after long-duration deep dives. Atmospheric diving suits (ADS) may be used to isolate the diver from high ambient pressure. Crewed submersibles can extend depth range, and remotely controlled or robotic machines can reduce risk to humans.
The environment exposes the diver
The ancient technique of free-diving requires breath-holding, and world-class free-divers can hold their breath underwater up to depths of 214 metres and for more than four minutes. Apneists, in this context, are people who can hold their breath for a long time.
Hyperventilation.
Voluntary hyperventilation before beginning voluntary apnea is commonly believed to allow the person involved to safely hold their breath for a longer period. In reality, it will give the impression that one does not need to breathe, while