Firth of Clyde

The Firth of Clyde encloses the largest and deepest coastal waters in the British Isles, sheltered from the Atlantic Ocean by the Kintyre peninsula which encloses the outer firth in Argyll and Ayrshire, Scotland. The Kilbrannan Sound is a large arm of the Firth of Clyde, separating the Kintyre Peninsula from the Isle of Arran. Within the Firth of Clyde is another major island - the Isle of Bute. Given its strategic location, at the entrance to the middle/upper Clyde, Bute played a vitally important military (naval) role during World War II.

The Firth's climate enjoys the benefit of the Gulf Stream from America.

At its entrance the firth is some 26 miles (42 km) wide. Its upper reaches include an area where it is joined by Loch Long and the Gare Loch. This includes the large anchorage off Greenock known as the Tail of the Bank in reference to the sandbar which separates the firth from the estuary of the River Clyde. The Clyde is still almost 2 miles (3 km) wide at the sandbar, and its upper tidal limit is at the tidal Weir adjacent to Glasgow Green.