To perform this type of dive.
A style of diving into a body of water in which the surface impact is made mostly by one's abdomen.
To use a snorkel.
A snorkel parka.
A retractable tube fitted in diesel-engine submarines to allow sufficient ventilation that the engines may be used at periscope depth.
A hollow tube, held in the mouth, or mounted on and opening into a diving mask, used by swimmers for breathing underwater.