In Memoriam - USS O-9 (SS-70) - Foundered 20 June 1941

USS O-9 (SS-70), a 500-ton submarine, was commissioned in 1918.

During the First World War, she operated along the Atlantic coast. Although she was sent to Britain for combat, the war ended before she reached Europe.

After serving as a training ship, she was decommissioned in 1931 and spent the the next ten years in reserve status in Philadelphia, PA.

As American involvement in the Second World War loomed, production of new submarines was greatly increased, with nearly 100 submarines on order by early 1941. In early 1941, nine O-class submarines, including O-9 returned to active duty to serve as training vessels for the many new officers and crewmembers that the fleet would need.

On the morning of 20 June, 1941, O-9 submerged as part of her recommissioning. She failed to surface.

By that evening, debris from the submarine's interior was recovered, indicating that she had suffered a hull rupture and that the entire crew had almost certainly perished. Despite this, Navy divers attempted to locate the sunken submarine, diving to 432 feet and pushing their equipment far beyond the 300-foot limit that was the design depth at the time. Given the extreme depth and the apparent damage to the submarine, rescue efforts were terminated and a memorial was held on 22 June, 1941.


O-9's exact location was lost to time, but in 1997, Klein Sonar (now L-3 Communications - Klein Associates, Inc.) located the the wreckage using side-scan sonar.


The forward hull is intact, but the entire hull abaft the conning tower has been crushed by water pressure. Her diving planes are level, indicating she suffered a flooding accident while near her test depth of 200 feet (the water depth is 432 feet).

The exact location of the wreck has been kept secret and is known only the a few people in the US Navy.

In 2005, the History Channel premiered an episode of "Deep Sea Detectives" titled "The USS O-9: The Forgotten Sub of WWII".