USS Serpens
Late in the evening of 29 January 1945 USS Serpens was anchored off Lunga Beach. The Commanding Officer and seven others (an officer and six enlisted men), were ashore. The remaining 198 members of Serpens' crew and 57 members of an Army stevedore unit were onboard the ship, loading aerial depth charges into her holds.
During the loading, Serpens exploded. The force of the explosion was so great that it killed an Army soldier who was ashore. After the explosion, only the bow of the ship was visible. The rest had disintegrated, and the bow sank soon afterward. Only two sailors aboard survived the incident. The cause of the explosion was never completely determined. The loss of the Serpens remains the largest single disaster ever suffered by the U.S. Coast Guard (Wikipedia) who crewed the ship.
The Serpens lies in 40 meters of water inshore from the John Penn and, even though the destruction of the ship was complete, there are large sections and much of her cargo remaining on the bottom. Due to the relative shallow depth there is plenty of time to explore.