The HMS Seaspite. (TV: The Sea Devils)
The HMS Seaspite was a Royal Naval Base located on Fortress Island. It was commanded by Captain John Hart, who was assisted by Third Officer Jane Blythe.
The Third Doctor and Jo Grant visited Seaspite during the Sea Devil crisis. The base came under attack by the Sea Devils living under an abandoned sea-fort close to the Island but the Naval Officers fought them off with the help of the Doctor. (TV: The Sea Devils)