To dive down in a steep angle.
To perform a rapid fall in price or value.
A rapid fall, e.g. in price or value.
A headfirst fall or jump.
A drop in altitude with the nose of the craft angled downwards.
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.