Salvage tug

French salvage tug Abeille Bourbon which also serves as an emergency tow vessel (ETV)
USNS Grapple Example of modern naval rescue and salvage ship

A salvage tug, also known historically as a wrecking tug, is a specialized type of tugboat that is used to rescue ships that are in distress or in danger of sinking, or to salvage ships that have already sunk or run aground.