page_title: Midget submarine
section_title: United States
hierarchical_section_title: Midget submarine / Types by nation / United States
context_page_description: A midget submarine is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to 6 or 9, 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.
  Both military and civilian midget submarines have been built. Military types work with surface ships and other submarines as mother ships. Civilian and non-combatant military types are generally called submersibles and normally work with surface ships.
  Most early submarines would now be considered midget submarines, such as the United States Navy's USS Holland and the British Royal Navy's HMS Holland 1.
context_section_description: Advanced SEAL Delivery System (ASDS): a former US Navy submersible used for clandestinely transporting Navy SEALs from a larger submarine to and from a mission site. The ASDS was canceled in 2009 due to cost overruns and reliability issues, and the only sub was destroyed in a fire in 2008.
  Aluminaut: the first aluminium submarine, used to recover sunken items, including DSV Alvin and an unarmed nuclear bomb.
  Bathyscaphe Trieste II (DSV-1): a sister ship to the Swiss-built Bathyscaphe Trieste, which was the first vessel to reach the bottom of the Challenger Deep, the lowest point in the oceans
  DSV Alvin (DSV-2): a research submersible operated by the Woods Hole Oceanographic Institute since 1964. Alvin has performed thousands of dives, including one that explored the wreck of the RMS Titanic, and its work in marine biology and oceanography has been featured in many scientific papers.
  DSV Turtle (DSV-3) of the Alvin class
  DSV Sea Cliff (DSV-4) of the Alvin class
  Nemo (DSV-5): an acronym for Naval Experimental Manned Observatory, a test vehicle operated by the Navy from 1970 to 1986. Nemo was a spherical submersible with a transparent acrylic hull, and its primary purpose was to evaluate the utility of the panoramic vision enabled by its design. Nemo was found to be an effective observation platform, despite not being able to hover in place, and acrylic-hulled submersibles have continued to be built and operated in the US.
  DSRV-1 Mystic: a Deep Submergence Rescue Vehicle formerly operated by the US Navy. Mystic was replaced by the Submarine Rescue Diving Recompression System (SRDRS) in 2008 and donated to the Naval Undersea Museum.
  DSRV-2 Avalon: a Deep Submergence Rescue Vehicle formerly operated by the US Navy. Avalon has been replaced by the Submarine Rescue Diving Recompression System and was donated to the Morro Bay Maritime Museum.
  Dry Combat Submersible (DCS): a US Navy submarine under development by Lockheed Martin for transporting Navy SEALs to and from a mission site. It is the planned replacement for the cancelled Advanced SEAL Delivery System.
  USS X-1: an experimental US Navy midget submarine of the 1950s, used to explore how to defend harbors against attacks by very small submarines.
caption: The US X-1 at sea
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