 Complete the following phrase:  Alvins first deep sea tests took place off Andros Island, the Bahamas, where it made a successful 12-hour, unmanned tethered test dive. On 20 July 1965 Alvin made its first manned dive for the Navy to obtain certification. On 17 March 1966, Alvin was used to locate a submerged 1.45-megaton hydrogen bomb lost in a United States Air Force 