DSRVs were developed as a result of the USS Thresher submarine accident in 1963, when all hands were lost. At the time, submarine operating depths greatly exceeded the capabilities of rescue vessels. The Deep Submergence Systems Project contracted with Lockheed Missiles and Space, Co. to produce a deep diving rescue submarine, the first of which was launched in 1970.
The primary mission of the DSRV is to provide a quick reaction, worldwide, all-weather capability to rescue personnel from submerged, disabled submarines (DISSUB) of the U.S. Navy or foreign navies at depths up to 2000 feet. The maximum operating depth is approximately 5000 feet. Mystic can be transported by truck, aircraft, surface ship, or on a mother submarine. For a rescue operation, it can dive, locate the DISSUB, and attach itself to the DISSUB's rescue seat. After the DSRV is properly attached to the submarine, the DISSUB's access hatches are opened and submarine personnel can directly the DSRV. The DSRV then detaches from the submarine and transfers the rescued personnel to the support ship.