The Swimmer Delivery Vehicle (SDV) is a type of non-propulsion torpedo that is designed to transport combat swimmers from a combat swimmer unit or naval Special Forces underwater, over long distances to and from maritime mission objectives on land or at sea. SDVs can carry their own onboard compressed air supply to extend the range of a swimmer's own air tank or rebreather equipment. The SDV can go as fast as 115 miles per hour. To reach such speeds, the vehicle needs to make use of supercavitation. A bubble of gas is generated around an object, reducing drag and making high speed underwater possible. It is equipped with a camera on its front, as well as thermal imaging and night-vision capabilities. It is developed by DARPA.
Solid Snake used an SDV during the Shadow Moses Incident to gain access to Shadow Moses Island. It was launched from from a torpedo tube on board the submarine Discovery, which could not get too close to the island, as the facility located there was equipped with sonar detection equipment. Since the SDV used no engine, it did not carry the same risk.