Diffuser (breathing set part)

A diffuser is a device fitted over an underwater breathing set's exhaust hole to break up the resulting bubbles small so they will not be seen from out of the water, and make less noise (see acoustic signature). They are used in:

• Combat diving (see frogman), to avoid detection by surface guards or by underwater hydrophones.
• Mostly, in underwater mine operations conducted by clearance divers, to make less noise, as acoustic mines are designed to explode when they detect particular sounds.
• In marine biology, to avoid disruption of fish behavior.