DSRV-1 Mystic is a Deep Submergence Rescue Vehicle. It was built by Lockheed for the U.S. Navy at a construction cost of $41 million and launched 24 January 1970. It was declared fully operational in 1977 and named Mystic.
DSRVs were designed for quick deployment in the event of a submarine accident and are transportable by truck, aircraft, ship, or specially configured attack submarine. The sub was capable of descending to 5,000 feet below the surface and could carry 24 passengers at a time in addition to its crew.