25 March 1915 – Tragedy struck the Submarine Service for the first time on this date in 1915. Off the Coast of Oahu, Submarine F-4 (SS 23) exploded and sank outside of Pearl Harbor. Twenty-One of the crew perished, the sole crew member to survive was one who was left ashore to collect any messages for the boat while it was underway. The ‘F’ class boat was one of the first stationed at the new submarine facility at Pearl. It was located in 300 feet of water opposite of Fort Armstrong. Attempts at salvage proved ineffective until specially fabricated pontoons were used and the boat was brought to the surface. During salvage operations a diver was awarded the Medal of Honor for rescuing another diver. An investigation determined that the lead lining of the battery well allowed salt water to leak into the battery. The F-4 remains were taken back out to sea and abandoned.