In March, 1921, a Navy tugboat, the U.S.S. Conestoga [navy.mil], set sail into choppy seas from San Francisco to Pearl Harbor, Hawaii, but she never reached her destination. Neither the ship nor any of the 56 crewmen were ever found and she became the last US Navy vessel to be lost at sea during peacetime. In 2009, NOAA was conducting a seafloor scan in the Greater Farallones National Marine Sanctuary [noaa.gov] and discovered a possible shipwreck. The site was investigated in 2014 and confirmed to be the missing ship [noaa.gov], thus putting to rest a 95 year mystery.
"Thanks to modern science and to cooperation between agencies, the fate of Conestoga is no longer a mystery," said Assistant Secretary of the Navy for Energy, Installations and Environment Dennis V. McGinn. "In remembering the loss of the Conestoga, we pay tribute to her crew and their families, and remember that, even in peacetime, the sea is an unforgiving environment."