Air hoses are used in underwater diving (e.g., scuba diving) to carry air from the surface or from air tanks. (See also Snorkel.) Scuba divers exploring fish and coral. ... An open surface with X-, Y-, and Z-contours shown. ... Snorkel A snorkel (also spelled schnorkel or schnorchel) is a tube that allows a person, vehicle, or vessel to draw air while submerged under water. ...