A frogman is someone who is trained in scuba diving or swimming underwater in a tactical capacity that includes military, and in some European countries, police work. Such personnel are also known by the more formal names of combat diver, combatant diver, or combat swimmer. The word frogman first arose in the stage name The Fearless Frogman of Paul Boyton in the 1870s and later was claimed by John Spence, an enlisted member of the U.S. Navy and member of the OSS Maritime Unit, to have been applied to him while he was training in a green waterproof suit.
A dry deck shelter (DDS) is a removable module that can be attached to a submarine to allow divers easy exit and entrance while the boat is submerged. The host submarine must be specially modified to accommodate the DDS, with the appropriate mating hatch configuration, electrical connections, and piping for ventilation, divers' air, and draining water. The DDS can be used to deploy a SEAL Delivery Vehicle submersible, Navy divers, or Combat Rubber Raiding Craft (CRRC).
A diver propulsion vehicle (DPV), also known as an underwater propulsion vehicle, sea scooter, underwater scooter, or swimmer delivery vehicle (SDV) by armed forces, is an item of diving equipment used by scuba divers to increase range underwater. Range is restricted by the amount of breathing gas that can be carried, the rate at which that breathing gas is consumed, and the battery power of the DPV. Time limits imposed on the diver by decompression requirements may also limit safe range in practice. DPVs have recreational, scientific and military applications.
A midget submarine is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to six or nine, with little or no on-board living accommodation. They normally work with mother ships, from which they are launched and recovered and which provide living accommodation for the crew and support staff.
The SEAL Delivery Vehicle (SDV) is a crewed submersible and a type of swimmer delivery vehicle used to deliver United States Navy SEALs and their equipment for special operations missions. It is also operated by the Royal Navy's Special Boat Service, which operates three SDVs.
Human torpedoes or manned torpedoes are a type of diver propulsion vehicle on which the diver rides, generally in a seated position behind a fairing. They were used as secret naval weapons in World War II. The basic concept is still in use.
The Advanced SEAL Delivery System (ASDS) was a midget submarine operated by the United States Navy and United States Special Operations Command. It provided stealthy submerged transportation for United States Navy SEALs from the decks of nuclear submarines for use as an insertion platform for covert and clandestine special operations missions. The ASDS was canceled in 2009 due to cost overruns and reliability issues, after the prototype was destroyed in a fire in 2008. As of 2019, the Navy plans to replace the ASDS with the Dry Combat Submersible, a similar midget submarine being developed by Lockheed Martin.
A wet sub is a type of underwater vehicle, either a submarine or a submersible, that does not provide a dry environment for its occupants. It is also described as an underwater vehicle where occupants are exposed to ambient environment during operations. The watercraft is classified as medium-sized or small vessel. This type of submarine differs from other underwater personal transport devices by the fact that it has a hull around it and it is not a "bare bones" design.
Naval Special Warfare Group 3 (NSWG-3), based at the Naval Amphibious Base Coronado in California, was one of six constituent formations of the United States Naval Special Warfare Command. Until 2008, NSWG-3 was composed of two SEAL Delivery Vehicle Teams: SDVT-1 in Pearl Harbor and SDVT-2 in Little Creek. In 2008, SDVT-2 was disestablished and merged into SDVT-1, which was then now headquartered in Pearl Harbor and operated detachments in Pearl Harbor and Little Creek. SDV Teams are SEAL teams with an added underwater delivery capability. SDVT-2 was reactivated on 8 March 2019. NSWG-3 was deactivated alongside NSWG-10 in August 2021 and replaced by Naval Special Warfare Group 8 which took in all units previously under NSWG-3 and NSWG-10.
Operation Thunderhead was a highly classified combat mission conducted by U.S. Navy SEAL Team One and Underwater Demolition Team 11 (UDT-11) in 1972. The mission was conducted off the coast of North Vietnam during the Vietnam War to rescue two U.S. airmen said to be escaping from a prisoner of war prison in Hanoi. The prisoners, including Air Force Colonel John A. Dramesi were planning to steal a boat and travel down the Red River to the Gulf of Tonkin.
The Cosmos-class submarine, officially Cos.Mo.S MG-110 locally designated as X-Craft, are the class of midget submarines designed by the Italian firm Cos.Mo.S, in Karachi Naval Dockyard in Karachi, Sindh, Pakistan.
The SX-404-class submarine, was a class of midget submarines produced by the Italian firm Cos.Mo.S.
CosMoS CE2F were a series of Swimmer Delivery Vehicle (SDV) built by M/s Cos.Mo.S Spa. which was based in Livorno, Italy.
The R-2 Mala is a class of swimmer delivery vehicles (SDVs) built for the Yugoslav, and later on, Croatian Navy. The two man wet SDVs are used for transporting naval commandos into hostile waters where they would perform sabotage on enemy warships and coastal installations. Weapons at their disposal included limpet mines.
The Indian Navy has been focusing on developing indigenous platforms, systems, sensors and weapons as part of the nation's modernisation and expansion of its maritime forces. As of November 2022, the Indian Navy has 45 vessels of various types under construction, including destroyers; frigates; corvettes; conventional-powered and nuclear-powered submarines and various other ship, and plans to build a strong navy of 200 vessels and 500 aircraft by 2050. According to Chief of Naval Staff's statement in December 2020, India has transformed from a buyer's navy to a builder's navy.
The Shallow Water Combat Submersible (SWCS) is a crewed submersible and a type of swimmer delivery vehicle that is planned to be used to deliver United States Navy SEALs and their equipment for special operations missions. It will replace the current Mark 8 SEAL Delivery Vehicle. The Navy planned to introduce the SWCS in 2018, although "slippage in the development" has delayed its introduction until 2019. In 2020, the U.S. Navy stated that it was undergoing sea trials and testing. As of October 2018, two subs have been delivered to the Navy while another two were in production. The SWCS will serve alongside the Dry Combat Submersible (DCS), a midget submarine with a dry interior being developed by Lockheed Martin as a replacement for the cancelled Advanced SEAL Delivery System (ASDS).
The Dry Combat Submersible (DCS) is a midget submarine delivered to USSOCOM by Lockheed Martin.
Cos.Mo.S, officially Costruzione Motoscafi Sottomarini s.a.s, was an Italian submarine and submersible manufacturer.
Drass, or DRASS, is an Italian manufacturing company headquartered in Livorno, whose best known for their range of midget submarine and swimmer delivery vehicle. They also have a line of hyperbaric chambers for diver decompression.
Al-Sabehat is a swimmer delivery vehicle built and operated by Iran. The SDV is approximately 8 m long, and carries a crew of 2 plus 3 divers. It can carry out coastal reconnaissance missions, planting naval mines on ports and anchorages, as well as lifting special forces. According to Abhijit Singh, a senior fellow at Observer Research Foundation, the SDV "can be used effectively for unconventional attacks".
Indian Navy 
