HMS Scylla.

 Ex HMS Scylla being prepared, then scuttled to form a marine reef. 

HMS Scylla was sunk in 2004 as an artificial reef 600m to the west of the Liberty ship James Eagan Layne in a project managed by the National Marine Aquarium in Plymouth. HMS Scylla (F71) was a 2500 ton Royal Navy Leander class frigate, she was the last frigate to be built at Devonport dockyard, launched in August 1968 and commissioned in 1970.

http://www.shipsproject.org/Wrecks/Wk_Scylla.html