Lake, Cumbria, England. Located in the Lake District, it is about 3 mi (5 km) long and 0.5–1.25 mi (0.8–2 km) wide, with a maximum depth of 72 ft (22 m). The River Derwent enters its southern end and leaves the lake's northern end near the market town of Keswick. Several sites on its shores are National Trust property and are frequented by tourists. Lords Island, one of several in the lake, was once the residence of the earls of Derwentwater.