The 2,781grt steam oiler Prudentia sank at Scapa Flow on 12 January 1916. She was lying alongside the oil storage vessel Hermione when, during a severe gale, she dragged her anchor. Her port shell plating was ruptured by Hermione’s anchor – she flooded and went to the bottom of the Flow. This wreck has, for fear of pollution, been off limits to divers since 1977 – however during the survey of HMS Vanguard, the survey team was granted rare access to inspect the wreck. Here’s the link to a short video of diving the wreck.