Snorkel (swimming)

A snorkel is a device used for breathing air from above the surface when the wearer's head is face downwards in the water with the mouth and the nose submerged. It may be either separate or integrated into a swimming or diving mask. The integrated version is only suitable for surface snorkeling, while the separate device may also be used for underwater activities such as spearfishing, freediving, finswimming, underwater hockey, underwater rugby and for surface breathing with scuba equipment. A swimmer's snorkel is a tube bent into a shape often resembling the letter "L" or "J", fitted with a mouthpiece at the lower end and constructed of light metal, rubber or plastic. The snorkel may come with a rubber loop or a plastic clip enabling the snorkel to be attached to the outside of the head strap of the diving mask. Although the snorkel may also be secured by tucking the tube between the mask-strap and the head, this alternative strategy can lead to physical discomfort, mask leakage or even snorkel loss. To comply with the current European standard EN 1972 (2015), a snorkel for users with larger lung capacities should not exceed 38 centimeters (15") in length and 230 cubic centimeters (14 cu. in.) in internal volume, while the corresponding figures for users with smaller lung capacities are 35 cm (14") and 150 cc (91⁄4 cu. in.) respectively. Current World Underwater Federation (CMAS) Surface Finswimming Rules (2017) require snorkels used in official competitions to have a total length between 43 and 48 cm (17" and 19") and to have an inner diameter between 1.5 and 2.3 cm (1⁄2" and 1"). A longer tube would not allow breathing when snorkeling deeper, since it would place the lungs in deeper water where the surrounding water pressure is higher. The lungs would then be unable to inflate when the snorkeler inhales, because the muscles that expand the lungs are not strong enough to operate against the higher pressure. The pressure difference across the tissues in the lungs, between the blood capillaries and air spaces would increase the risk of pulmonary edema.