Ullswater is the second-largest lake in the English Lake District, stretching 12 kilometres through a glacially carved valley with fells rising steeply on both sides. It is widely considered the most scenically dramatic of the Lakeland lakes — the combination of scale, mountain backdrop, and the serpentine curve of the lake means you rarely see all of it at once.
The lake supports swimming, kayaking, paddleboarding, and sailing. Wild swimming is popular at several points along the shores, particularly off the eastern bank near Howtown. The water is cold year-round but swimmable in summer. Paddleboard and kayak rentals are available from Ullswater Outdoor in Glenridding. The lakeshore is almost entirely undeveloped, which is what makes it so visually powerful.