HMNB Portsmouth in the context of "Mary Rose Museum"

A naval base, navy base, or military port is a military base, where warships and naval ships are docked when they have no mission at sea or need to restock. Ships may also undergo repairs. Some naval bases are temporary homes to aircraft that usually stay on ships but are undergoing maintenance while the ship is in port.

In the United States, the United States Department of the Navy's General Order No. 135 issued in 1911 as a formal guide to naval terminology described a naval station as "any establishment for building, manufacturing, docking, repair, supply, or training under control of the Navy. It may also include several establishments". A naval base, by contrast, was "a point from which naval operations may be conducted".

His Majesty's Naval Service, referred to colloquially as the Royal Navy, after the primary fighting arm of the service, is the United Kingdom's naval warfare and maritime service. It consists of the Royal Navy, Royal Marines, Royal Fleet Auxiliary, Royal Naval Reserve, Royal Marines Reserve and Naval Careers Service. The Naval Service as a whole falls under the command of the Navy Board, which is headed by the First Sea Lord. This position is currently held by General Sir Gwyn Jenkins (appointed May 2025). The Defence Council delegates administration of the Naval Service to the Admiralty Board, chaired by the Secretary of State for Defence.

The Naval Service is dominated by the Royal Navy, and operates primarily from three bases in the United Kingdom where commissioned ships are based; Portsmouth, Clyde and Devonport, the last being the largest operational naval base in Western Europe. As of December 2025, there were about 90 vessels in service with the various branches of the Naval Service, plus more than 90 additional vessels operated by the supporting Serco Marine Services. These vessels included: 63 commissioned ships of the Royal Navy, 17 principal landing craft of the Royal Marines, 10 auxiliary ships of the Royal Fleet Auxiliary and 90+ supporting Marine Services vessels. Additional vessels are under charter to the Ministry of Defence. As of 2022, HM Naval Service (Royal Navy, Royal Marines, Royal Fleet Auxiliary and Naval Careers Service) employed about 39,500 regular and reserve personnel.

Gosport (/ˈɡɒspɔːrt/ GOS-port) is a town and non-metropolitan district with borough status in Hampshire, England. At the 2021 Census, the town had a population of 70,131 and the district had a population of 81,952. Gosport is situated on a peninsula on the western side of Portsmouth Harbour, opposite the city of Portsmouth, to which it is linked by the Gosport Ferry.

Until the last quarter of the 20th century, Gosport was a major naval town associated with the defence and supply infrastructure of His Majesty's Naval Base (HMNB) Portsmouth. As such over the years extensive fortifications were created. Gosport is still home to HMS Sultan and a Naval Armament Supply Facility, as well as a helicopter repair base.

His Majesty's Naval Base, Devonport (HMNB Devonport) is one of three operating bases in the United Kingdom for the Royal Navy (the others being HMNB Clyde and HMNB Portsmouth) and is the sole nuclear repair and refuelling facility for the Royal Navy. HMNB Devonport is located in Devonport, in the west of the city of Plymouth, England.

The base began as a Royal Navy Dockyard in the late 17th century, designed and built on open ground by Edmund Dummer as an integrated facility for the repair and maintenance of warships, centred on his pioneering stone dry dock (one of the earliest stepped docks in the world). Over the next two centuries it expanded, reaching its present extent in the 20th century. Historically, the yard was also used for shipbuilding: over 300 naval vessels were built there, the last being HMS Scylla (launched in 1968).

His Majesty's Naval Base, Clyde (HMNB Clyde; also HMS Neptune), primarily sited at Faslane on the Gare Loch, is one of three operating bases in the United Kingdom for the Royal Navy (the others being HMNB Devonport and HMNB Portsmouth). It is the navy's headquarters in Scotland and is best known as the home of Britain's nuclear weapons, in the form of nuclear submarines armed with Trident missiles.

The Royal Marines Band Service is the musical wing of the Royal Navy and an independent element of the Royal Marines. It currently consists of five military bands plus a training wing – the Royal Marines School of Music at HMS Nelson – and its headquarters is at HMS Excellent, Whale Island, Portsmouth.

Serco Marine Services is a Private Finance Initiative contract, with Serco Group, to deliver auxiliary services to His Majesty's Naval Service (incl. Royal Navy, Royal Marines and Royal Fleet Auxiliary).

Marine Services primarily operates from the nation's three main naval bases, HMNB Portsmouth, HMNB Devonport and HMNB Clyde, but also supports training and operations overseas, as well as at various British Overseas Territories.