What was the reason for naval supremacy pf British and why is it no more?

Answer 1

WE ARE STILL THE SECOND LARGEST NAVY IN THE WORLD

I think maybe being an island nation has something to do with it.

The Royal Navy of the United Kingdom is the oldest of the British armed services (and is therefore the Senior Service). From the early 18th century to the middle of the 20th century, it was the largest and most powerful navy in the world, helping to establish the British Empire as the dominant power of the 18th, 19th and early 20th centuries. During the Cold War, it was transformed into primarily an anti-submarine force, hunting for Soviet submarines, being mostly active in the North Atlantic Ocean. With the collapse of the Soviet Union, its role for the 21st century has returned to focus on global expeditionary (blue water) operations.

The Royal Navy is the second largest navy in the world in terms of gross tonnage. There are currently 90 commissioned ships in the Royal Navy, including aircraft carriers, submarines, mine counter-measures and patrol vessels as well as the ships of the Royal Fleet Auxiliary.

The Royal Navy is a constituent component of the Naval Service, which also comprises the Royal Marines, Royal Fleet Auxiliary and associated reserve forces under command. The Naval Service had 39,400 regular personnel as of April 2006.


Role
The role of the Royal Navy (RN) is to protect British interests at home and abroad, executing the foreign and defence policies of Her Majesty's Government through the exercise of military effect, diplomatic activities and other activities in support of these objectives. The RN is also a key element of the UK contribution to NATO, with a number of assets allocated to NATO tasks at any time. These objectives are delivered via a number of capabilities:

Maintenance of the UK Nuclear Deterrent through a policy of Continuous at Sea Deterrence
Delivery of the UK Commando force
Contribution of assets to Joint Force Harrier
Contribution of assets to the Joint Helicopter Command
Maintenance of standing patrol commitments; Atlantic Patrol Task (North), Atlantic Patrol Task (South), Persian Gulf patrols etc.
Delivery of Mine Counter Measures capability to UK and allied commitments
Provision of Hydrographic and meteorological capabilities deployable worldwide
Protection of UK and EU fisheries