by Gareth Collins

Biber I: One man submersible about 8 metres in length with a fixed periscope of about 1.5 metres in length. It had a 6 cylinder Opel petrol engine with 32hp and an electro-engine. It had a speed of 6.5 nautical miles per hour and the pilot breathed through an oxygen tank. It was armed with 2 outboard torpedos. It was put into operation with great losses.

Biber II: Two-man submersible with a diesel rotation engine producing 65hp. In all other aspects it was like the Biber I except it had simplified operations and a reserve driver. It had two outboard torpedoes. It was never used operationally.