Tonelero (S21) was an Oberon-class submarine in the Brazilian Navy. It was ordered on 22 May 1970, and commissioned on 8 September 1978. Tonelero was seriously damaged by fire during the ship's fitting out and was sent to HM Dockyard Chatham to undergo repairs. The central section of the pressure hull was cut out and replaced, and all electrical wiring was replaced. This delayed the completion of the boat until 1978. Tonelero was the last of Oberon-class to be completed by Vickers.