Penguin In A Diving Suit

Underwater diving is the practice of going underwater, either with breathing apparatus (scuba diving and surface supplied diving) or by breath-holding (free-diving).
Recreational diving is a popular activity (also called sports diving or subaquatics). Professional diving (commercial diving or diving for financial gain) takes a range of diving activities to the underwater work site.
Levels of training and types of equipment and breathing gases used differ between types of diving.