Coniston Water in Cumbria, England is the third largest lake in the English Lake District. It is five miles (8 km) long, half a mile (800 m) wide, has a maximum depth of 184 feet (56 m), and covers an area of 1.89 square miles (4.9 km2). The lake has an elevation of 143 feet (44 m) above sea level. It drains to the sea via The River Crake.
Coniston is situated within the boundaries of the historic county of Lancashire. Today Coniston forms part of the administrative county of Cumbria. Coniston Water is an example of a ribbon lake formed by glaciation. The lake sits in a deep U-shaped glaciated valley scoured by a glacier in the surrounding volcanic and limestone rocks during the last ice age. To the north-west of the lake rises the Old Man of Coniston, the highest fell in the Coniston Fells group.