The Siluro was an underwater camera made by Nemrod Metzeler in Barcelona, Spain between c.1960 and 1966.
The body is a plastic cylinder with a sports finder at the top, a large handle on the user's left and a hinged front. It is equipped with valve to allow pressurising the interior to ensure good sealing, allowing it to operate to depths of 40m. There are some ballast lead weights built in. Single speed shutter (~1/55s) with an f16 fixed-focus lens set to a depth-of-field of around 1-2.5m. The camera is usually shown with a flash gun fitted in front of the handle.
Film format is 12 6x6cm exposures on 120 film.
The Mako Shark is a similar camera, but for 620 film - and without flash sync.