A frogman is someone who is trained in scuba diving or swimming underwater in a tactical capacity that includes military, and in some European countries, police work. Such personnel are also known by the more formal names of combat diver, combatant diver, or combat swimmer. The word frogman first arose in the stage name the "Fearless Frogman" of Paul Boyton in the 1870s and later was claimed by John Spence, an enlisted member of the U.S. Navy and member of the OSS Maritime Unit, to have been applied to him while he was training in a green waterproof suit.
A SEAL Delivery Team member climbs aboard a delivery vehicle before launching from the back of the submarine USS Philadelphia.
A 1945 British navy frogman with complete gear, including the Davis apparatus, a rebreather originally conceived in 1910 by Robert Davis as an emergency submarine escape set.
A French frogman with chest counterlung loop rebreather with two breathing tubes (model "Oxygers", 1957).
Royal Navy divers in Sladen suits during World War II
Scuba diving is a mode of underwater diving whereby divers use breathing equipment that is completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. The name scuba is an anacronym for "Self-Contained Underwater Breathing Apparatus" and was coined by Christian J. Lambertsen in a patent submitted in 1952. Scuba divers carry their own source of breathing gas, usually compressed air, affording them greater independence and movement than surface-supplied divers, and more time underwater than free divers. Although the use of compressed air is common, a gas blend with a higher oxygen content, known as enriched air or nitrox, has become popular due to the reduced nitrogen intake during long or repetitive dives. Also, breathing gas diluted with helium may be used to reduce the effects of nitrogen narcosis during deeper dives.
Recreational scuba diver
The undersea kelp forest of Ana Capa off of the coast of Oxnard, California
Diver looking at a shipwreck in the Caribbean Sea.
Sidemount diver pushing a cylinder in front