Rydal Water is a small body of water in the central part of the English Lake District, in the county of Cumbria. It is located near the hamlet of Rydal, between Grasmere and Ambleside in the Rothay Valley.
The lake is 1,290 yards long and varies in width up to a maximum of 380 yards, covering an area of 0.12 mi². It has a maximum depth of 55 ft and an elevation above sea level of 177 ft. The lake is both supplied and drained by the river Rothay, which flows from Grasmere upstream and towards Windermere downstream.
The waters of the southern half of the lake are leased by the Lowther Estate to the National Trust, whilst those of the northern half belong to the estate of Rydal Hall. Navigation is prohibited, except for residents of Rydal Hall.
Numerous walks are possible in the surrounding hills, as well as a walk around the lake itself, which takes in Dove Cottage and Rydal Mount, both homes to William Wordsworth, and Rydal Cave, a former quarry working. At the western end of the lake, steps lead to Wordsworth's Seat, which is considered to have been Wordsworth's favourite viewpoint in the Lake District.