Faslane Naval Base, officially HMS Neptune, is a Royal Navy base situated on Gare Loch, which connects to the River Clyde in Scotland. The base serves as home base to the UK's fleet of Trident nuclear armed submarines, as well as conventional nuclear submarines. Together with Coulport naval base on nearby Loch Long Faslane forms HM Naval Base Clyde. Coulport acts as the storage facility for Trident.

Faslane was first constructed and used as a base in World War II. During the 1960s, the United Kingdom began negotiations with the United States of America regarding the purchase of a Polaris nuclear missile system to be fired from 5 specially constructed submarines. In the end, only four were constructed:

• HMS Resolution
• HMS Repulse
• HMS Renown
• HMS Revenge

These four submarines were permanently based at Faslane. One boat was always on patrol at any given time. In times of political instability, sometimes two boats would be deployed at sea. In the 1980s, the British Government announced plans to replace the Polaris submarines with the newly developed Trident missile system, also to be based at Faslane. These submarines were named:

• HMS Vanguard
• HMS Victorious
• HMS Vigilant
• HMS Vengeance

Given the presence of these nuclear capable missiles, Faslane has attracted demonstrations by Campaign for Nuclear Disarmament and other Scottish pressure groups, including Trident Ploughshares. A permanent peace camp is outside the base gates, and there are frequent demonstrations at the base gates. The presence of Faslane is also an issue in Scottish politics. The Scottish National Party, the Scottish Socialist Party and the Scottish Green Party all oppose the deployment of nuclear weapons, although the Scottish National Party have made assurances that they would retain the base for the servicing of conventionally-armed and powered naval units. It is not unusual for members of these parties, and indeed some from the Labour Party, to attend rallies outside Faslane. Such events aim to keep the base closed for as long as possible by preventing its staff from arriving for work, and usually involve large numbers of protestors being arrested for non-violent civil disobedience.

Faslane is also home to the Royal Navy's other classes of submarine, including the fleet of hunter-killer submarines: the Trafalgar class; and the Swiftsure class. The Royal Navy has announced that the Astute-class SSN will also be based at Faslane.