(From Lat. Aqua — water and Eng. Lung — lung), bus. backpack device for breathing underwater. Speleo-tourists used to overcome the siphon into the caves in the survey of underground lakes and rivers, water tourists and backpackers in the survey of ground water, as well as athletes, seamen and prof. divers during underwater work at depth. 40 MA used in caving, consist of 1 — 4 can of compressed air (under pressure of 12 — 20 MPa), 1 — 2 independent motors and lung machines with mouthpiece, external gauge and pointer min. pressure Connect the. tubes of high and low pressure and straps. Backpackers water tourists and athletes tend to use more simple design A with a 1-2 tanks and one gear.