SAN DIEGO -- The Navy has retired the last of its mini-rescue subs built after the 1963 sinking of a nuclear-powered submarine during deep water diving tests.

Navy officials say the Mystic was retired on Wednesday. The 49-foot-long mini-sub was operated by the Navy's Deep Submergence Unit based in San Diego.

The Mystic, which can dive up to a mile below the ocean's surface, was built after the sinking of the USS Thresher killed all on board.

Navy officials say the mini-sub never carried out a real underwater rescue, although it was featured in several movies and television shows, including the short-lived NBC television series "Surface."