USS Tunxis, an 1175-ton Casco-class light draft monitor, was built at Chester, Pennsylvania. Commissioned in July 1864 as the first of her class, she was found to be completely unseaworthy as soon as she began her first voyage and was decommissioned in September 1864 for an extensive reconstruction. This work was not completed until July 1866, by which time the Civil War was long over and there was no further need for her in the active Navy. Accordingly, Tunxis was laid up at the League Island Navy Yard, Philadelphia, Pennsylvania. She had no further active service, but was twice renamed in 1869, becoming Hydra in June and Otsego in August. The monitor was scrapped in 1874.