Rivers and Lakes
Since Britain has a moist climate with much rainfall, rivers and lakes are numerous. Rivers in central and eastern Britain tend to flow slowly and steadily all year long because they are fed by the frequent rain. Many have been navigable, and from the earliest times they have served peoples interested in either commerce or invasion. The Highlands act as a divide and determine whether rivers flow west to the Irish Sea or east to the North Sea. Rivers and streams moving westward down from the Highlands tend to be swift and turbulent; rivers flowing eastward tend to be long, graceful, and gentle, with slowly moving waters.
The Thames and the Severn are the longest rivers in Britain and are almost equal in length. The Severn flows south out of the mountains of central Wales to the Bristol Channel at Bristol. It is 290 km (180 mi) long. The Thames, 338 km (210 mi) long, flows eastward out of the Cotswold Hills and weaves through the metropolis of London. The Thames provides water to the city of London and is used to carry commercial freight. Other important rivers in England are the Mersey, which enters the Irish Sea at Liverpool; the River Humber on the east coast, into which the Trent River and several other rivers flow; and the Tyne River in northern England, which flows past Newcastle upon Tyne to the North Sea.
In Scotland the important rivers are the Clyde and the Forth, which are joined by a canal. The River Clyde flows northwest, past Glasgow, and empties into the Atlantic at the Firth of Clyde. (Firth is the Scottish name for an arm of the sea that serves as the broad estuary of a river.) The River Forth flows eastward into the Firth of Forth, where Edinburgh rises on its south bank. The most important rivers in Northern Ireland are the Lagan, the Bann, and the Foyle.
Most of the large lakes in the United Kingdom are located in the upland areas of Scotland and northern England, although Lough Neagh in Northern Ireland is the largest lake in the United Kingdom. Loch Lomond, on the southwestern edge of the Highlands of Scotland, is the largest on the island of Great Britain, measuring 37 km (23 mi) long and from 1.6 to 8 km (1 to 5 mi) wide. Lake Windermere is the largest of the 15 major lakes in the famous Lake District of northwestern England. It is about 1.6 km (1 mi) wide and more than 16 km (10 mi) long.