Buttermere is a lake in the Lake District in North West England. The adjacent village of Buttermere takes its name from the lake. Historically in Cumberland, the lake is now within the county of Cumbria. Owned by the National Trust, it forms part of its Buttermere and Ennerdale property.

The lake is 1.25 miles (2,010 m) long by 0.25 miles (400 m) wide, and is 75 feet (23 m) deep.[1] It has an elevation above sea level of 329 feet (100 m). It is situated towards the head of the valley of the River Cocker and is surrounded by fells, notably the High Stile range to the south west, Robinson to the north-east, Fleetwith Pike and Haystacks to the south-east and Grasmoor to the north-west.
The village of Buttermere stands at the north-western end of the lake, and beyond this is Crummock Water. There is a path around the lake which is about 4.5 miles (7.2 km) long, and at one point runs through a rock tunnel beneath the locality of Hassness. Access is by road, from Cockermouth in the north-west; from Borrowdale via the Honister Pass; or from Braithwaite and the Newlands Valley via Newlands Hause.