During the final dive of the 2021 ROV Shakedown, we explored the wreck of Humaitá (ex-USS Muskallunge), an American submarine that served in two navies between 1942 and 1968 (U.S. and Brazilian). Sunk during a live-fire target exercise off Long Island, New York, in 1968, remains of the submarine serve as habitat for bubblegum corals (Paragorgia sp.) and other marine animals and are protected from unauthorized disturbance by federal law.