By: Naval History and Heritage Command Underwater Archaeology Branch

Yesterday, the National Oceanic and Atmospheric Administration (NOAA), with support from NHHC’s Underwater Archaeology Branch, announced that after almost 95 years, the mystery of USS Conestoga had been solved. The ship was discovered in 2009 and positively identified in 2015 in waters off of San Francisco, California. Here’s the timeline of events that led up to yesterday’s announcement at the Navy Memorial:
- 25 March 1921: at 0900, USS Conestoga left California bound for American Samoa by way of Pearl Harbor, Hawaii. She never arrived to her destination.
- 26 April 1921: Conestoga was overdue in her arrival to Pearl Harbor despite miscommunication on April 6 that she had arrived safely.
- 17 May 1921: The steamship Senator came across a derelict lifeboat with a brass letter “C” on its bow at 18º15′ N, 115º42′ W, some 650 miles west of Manzanillo, Mexico, and about 30 miles off Clarion Island.
- 30 June 1921: Navy officials retroactively declared Conestoga’s loss, with all 56 souls aboard lost.
- August 2009: An expedition through NOAA’s Office of Coast Survey aboard F/V Pacific Star revealed a previously undocumented multibeam sonar target. The target appeared to be a wrecked tug.
- September 2014: Upon further investigation using remotely operated vehicles (ROV) during a Maritime Heritage expedition aboard R/V Fulmar, researchers confirmed the target was a steel steam-powered tugboat that measured approximately 170 feet in length and 26 feet in beam. Archival research provided no clues to the identity of the tug beyond that of USS Conestoga.

- October 2015: As a potential U.S. Navy shipwreck, an NHHC representative joined NOAA on a follow-up survey at the site. Utilizing ROV, the survey provided further evidence towards the identification of the site as the wreck of USS Conestoga, one the Navy’s most mysterious losses. Given the features and dimensions of the wreck, including the presence of a 3-inch 50 caliber World War I-era gun, a steam-steered engine, and two Scotch marine boilers, archaeologists and researchers confirmed the wreck is that of Conestoga.


As a U.S. Navy ship, USS Conestoga remains Navy property and is protected under the Sunken Military Craft Act (SMCA). The SMCA states that Conestoga, and any other Navy ship or aircraft wreck, is not to be disturbed, removed, or injured, as violators may face enforcement action for doing so without authorization. During the investigation of the wreck, no remains of the crew were found, however, the wreck site remains a maritime grave site for the 56 Sailors lost. Because Conestoga also lies within NOAA’s Greater Farallones National Marine Sanctuary, it has the added benefit of resting in protected waters. The Navy will continue to monitor USS Conestoga as it does for many of its shipwrecks and aircraft wrecks to ensure continued preservation for future generations.
For more information about the USS Conestoga, including detailed reports of the wreck site, biographies of the Sailors lost and how the Navy determined it was the ship lost in 1921, click here.
