The AAI underwater revolver is an amphibious

firearm A firearm is any type of gun designed to be readily carried and used by an individual. The term is legally defined further in different countries (see Legal definitions). The first firearms originated in 10th-century China, when bamboo tubes ...

intended for naval use. The weapon was designed by Irwin R. Barr and John L. Critcher and uses a six-round cylinder inside a jacket covered by a float.

References

Cold War weapons of the United States Revolvers of the United States Underwater pistols Flechette firearms {{Revolver-stub