The Davis Submerged Escape Apparatus, was an early type of oxygen rebreather invented in 1910 by Sir Robert Davis, head of Siebe Gorman and Co. Ltd., inspired by the earlier Fleuss system, and adopted by the Royal Navy after further development by Davis in 1927. While intended primarily as an emergency escape apparatus for submarine crews, it was soon also used for diving, being a handy shallow water diving apparatus with a thirty-minute endurance, and as an industrial breathing set.

Lieutenant-Commander Lionel Kenneth Phillip Crabb,, known as Buster Crabb, was a Royal Navy frogman and diver who vanished during a reconnaissance mission for MI6 around a Soviet cruiser berthed at Portsmouth Dockyard in 1956.