Great Lakes

Most of the world's great lakes lie in regions that were once glaciated. The glaciers carved out deep hollows in the rock in which water collected. The Great Lakes of the USA and Canada are partly glacial in origin.

The world's deepest lakes are often formed by faults in the Earth's crust, such as Lake Baikal in Siberia and Lake Tanganyika in East Africa.

Most lakes last only a few thousand years before they are filled in by silt or drained by changes in the landscape. The world's oldest great lake is Lake Baikal in Siberia, which is over 2 million years old.

The Great Lakes include three of the world's five largest lakes: Superior, Huron and Michigan. The world's largest lake is the Caspian Sea, which is a huge saltwater lake below sea level. It covers 371,000 sq km.

The world's highest great lake is lake Titicaca in South America, which is 3812 m above sea level.

The world's lowest great lake is the Dead Sea between Israel and Jordan. It is 399 m below sea level and getting lower all the time.

The largest underground lake in the world is Drauchen-hauchloch, which is inside a cave in Namibia.