170915-N-SH284-022 KEYPORT, Wash. (Sept. 15, 2017) The original crew members of the Bathyscaphe Trieste, and its successor, Trieste II, pose for a photo in front of the Trieste II during the bi-annual reunion of the Bathyscaphe Trieste Alumni Association outside the Naval Undersea Museum-Keyport. Trieste is the only manned submarine ever to explore the deepest part of the ocean, the Challenger Deep in the Marianas Trench. Trieste II, the first deep submergence vehicle built by the U.S. Navy, following its acquisition of the original Trieste bathyscaphe, is permanently on display outside of the museum. (U.S. Navy photo by Mass Communication Specialist 2nd Class Vaughan Dill/Released)