HMS Otus, Military submarine museum in Sassnitz, Germany.

HMS Otus is a British Oberon-class submarine with a length of about 91 meters, equipped with eight torpedo tubes and original naval equipment from its operational years. The vessel is fully accessible and displays all main sections including the navigation room, torpedo compartment, and engine room.

HMS Otus was laid down by Scotts Shipbuilding and Engineering Company on 31 May 1961, launched on 17 October 1962 and commissioned on 5 October 1963. In July 1987, trials in Bjornafjorden near Bergen, Norway, set a world escape record of 183 metres, reached by Norman Cook and Hamish Jones. Otus served in the 1991 Gulf War under Operation Granby, returning to Gosport flying a Jolly Roger, and was decommissioned in April 1991. In June 2002 a German entrepreneur bought her and moored her in Sassnitz harbour on Rügen as a floating museum ship.

The vessel displays the living quarters and work spaces where the crew spent their time, showing how cramped the conditions were and how sailors managed daily life aboard. Visitors can understand the routines and challenges of serving in such confined spaces.

The vessel is open daily with longer hours during warmer months and shorter hours in winter, allowing visitors to explore the different sections. It is advisable to wear comfortable shoes since entering tight passageways and climbing stairs throughout the ship are necessary.

In July 1987, trials in Bjornafjorden near Bergen used Otus for progressively deeper escapes from 30 metres; two submariners reached 183 metres, a world record still unbroken. The first was a controlled ascent by Warrant Officer Norman Cook; the second, Petty Officer Hamish Jones, made an emergency release after giving the alarm while flooding the chamber. Both were unharmed and later received British Empire honours.