Diving is jumping or falling into water. It can also mean swimming beneath the surface of the water.
See also: Orbital skydiving.
Skindiving is diving without a wetsuit, using a snorkel. Once, Geordi La Forge went skindiving off the coral reef on Bracas V. He would later relate this experience when the Enterprise was being pulled through space by what appeared to be a school of two-dimensional lifeforms. (TNG: "The Loss")
Scuba diving Edit
Scuba diving is diving with special self-contained breathing equipment.
In 2365, a holoprogram available to crewmembers of the USS Enterprise-D was "Scuba Diving Hanauma Bay Earth". The program, with a code list number of 03-889, was listed in the exercise menu. (TNG: "The Emissary", okudagram)