The deepest dive in history has uncovered a WWII US Navy shipwreck four miles underwater. The USS Johnston was found east of Samar Island in the Philippines. The wreck was a US Navy Fletcher-class destroyer, sunk on October 25 1944 during the Battle of Leyte Gulf to liberate the Philippines from the Imperial Japanese. The manned expedition was undertaken by two former US Navy Officers with underwater technology firm Caladan Oceanic.