Bassenthwaite Lake is one of the largest water bodies in the English Lake District. It is long and narrow, approximately 4 miles (6.4 km) long and 3⁄4-mile (1.2 km) wide, but is also extremely shallow, with a maximum depth of about 70 ft (21 m).
It is the only body of water in the Lake District to be technically defined as a "lake" and to use the word "lake" in its name, all the others being "waters" (for example, Derwent Water), "meres" (for example, Windermere) or "tarns" (for example, Dock Tarn). It is fed by, and drains into, The River Derwent. The lake lies at the foot of Skiddaw, near the town of Keswick.