This S-Class (Group I) Overseas Patrol Submarine
was build in Chatham dockyard and commissioned in October 1933.
At the outbreak of WW2 it formed part of the 2nd
Flotilla but by 1940 it had been transferred to the 6th Flotilla.
Seahorse was lost on 7 January 1940 following a depth charge attack by the
German 1st Minesweeping Flotilla.