HMS Gotland (Gtd) is an attack submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

 of the Swedish Navy

Swedish Navy

The Royal Swedish Navy is the naval branch of the Swedish Armed Forces. It is composed of surface and submarine naval units – the Fleet – as well as marine units, the so-called Amphibious Corps .In Swedish, vessels of the Swedish Navy are given the prefix "HMS," short for Hans/Hennes...

. It is the first of the Gotland class

Gotland class submarine

In 2004, the Swedish government received a request from the United States of America to lease HMS Gotland – Swedish-flagged, commanded and manned, for a duration of one year for use in anti-submarine warfare exercises. The Swedish government granted this request in October 2004, with both...

, which is the first operational submarine class in the world to use air-independent propulsion

Air-independent propulsion

Air-independent propulsion is a term that encompasses technologies which allow a submarine to operate without the need to surface or use a snorkel to access atmospheric oxygen. The term usually excludes the use of nuclear power, and describes augmenting or replacing the diesel-electric propulsion...

 (AIP).

It was built by Kockums

Kockums

Kockums AB is a shipyard in Malmö, Sweden owned by the German shipyard Howaldtswerke-Deutsche Werft in Kiel. HDW itself is a subsidiary of the German ThyssenKrupp Marine Systems....

, launched in 1995 and subsequently commissioned in 1996. The AIP units use liquid oxygen

Liquid oxygen

Liquid oxygen — abbreviated LOx, LOX or Lox in the aerospace, submarine and gas industries — is one of the physical forms of elemental oxygen.-Physical properties:...

 with diesel as the propellant.

Lease to the United States Navy

In 2004, the Swedish government

Government of Sweden

The Government of the Kingdom of Sweden is the supreme executive authority of Sweden. It consists of the Prime Minister and cabinet ministers appointed by the Prime Minister. The Government is responsible for their actions to the Riksdag, which is the legislative assembly...

 received a request from the United States of America to lease HMS Gotland – Swedish-flagged, commanded and manned, for a duration one year for use in anti-submarine warfare

Anti-submarine warfare

Anti-submarine warfare is a branch of naval warfare that uses surface warships, aircraft, or other submarines to find, track and deter, damage or destroy enemy submarines....

 exercises. The Swedish government granted this request in October 2004, with both navies signing a memorandum of understanding

Memorandum of understanding

A memorandum of understanding is a document describing a bilateral or multilateral agreement between parties. It expresses a convergence of will between the parties, indicating an intended common line of action. It is often used in cases where parties either do not imply a legal commitment or in...

 on 21 March 2005.

Gotland was loaded onboard the Norwegian

Norway

Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...

 semi-submersible heavy-lift ship, MV Eide Transporter, on 10 May 2005, for a month-long voyage over the Atlantic Ocean

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 and through the Panama Canal

Panama Canal

The Panama Canal is a ship canal in Panama that joins the Atlantic Ocean and the Pacific Ocean and is a key conduit for international maritime trade. Built from 1904 to 1914, the canal has seen annual traffic rise from about 1,000 ships early on to 14,702 vessels measuring a total of 309.6...

 to Naval Base Point Loma

Naval Base Point Loma

Located in Point Loma, a neighborhood of San Diego, California, Naval Base Point Loma was established on 1 October 1998 when Navy facilities in the Point Loma area of San Diego were consolidated under Commander, Navy Region Southwest...

 in San Diego, California

San Diego, California

San Diego is the eighth-largest city in the United States and second-largest city in California. The city is located on the coast of the Pacific Ocean in Southern California, immediately adjacent to the Mexican border. The birthplace of California, San Diego is known for its mild year-round...

, where it arrived on 27 June 2005. After a couple weeks of getting accustomed to the new environment, the exercises with United States 3rd Fleet

United States 3rd Fleet

The Third Fleet is one of seven numbered fleets in the United States Navy. Third Fleet's area of responsibility includes approximately fifty million square miles of the eastern and northern Pacific ocean areas including the Bering Sea, Alaska, the Aleutian Islands and a sector of the Arctic...

 began on 18 July 2005. The lease was extended for another 12 months in 2006.

Gotland managed to penetrate the massive defensive measures of a carrier battle group

Carrier battle group

A carrier battle group consists of an aircraft carrier and its escorts, together composing the group. The first naval task forces built around carriers appeared just prior to and during World War II. The Imperial Japanese Navy was the first to assemble a large number of carriers into a single...

 undetected and snap several pictures of the during a wargaming

Wargaming

A wargame is a strategy game that deals with military operations of various types, real or fictional. Wargaming is the hobby dedicated to the play of such games, which can also be called conflict simulations, or consims for short. When used professionally to study warfare, it is generally known as...

 exercise in the Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, effectively "sinking" the aircraft carrier. The exercise was conducted to evaluate the effectiveness of the US Fleet against modern diesel-electric

Diesel-electric

Diesel-electric transmission or diesel-electric powertrain is used by a number of vehicle and ship types for providing locomotion.A diesel-electric transmission system includes a diesel engine connected to an electrical generator, creating electricity that powers electric traction motors...

 submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s, which some have noted as severely lacking.

In July 2007, Gotland departed San Diego for Sweden.