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 1290yd (1.18 km) long and varies in width up to a maximum of 380yd (350m), covering an area of 0.12 mi² (0.31 km²). It has a maximum depth of 65 ft (17m) and an elevation above sea level of 177 ft (54m). The lake is both supplied and drained by the river Rothay, which flows from Grasmere upstream and towards Windermere downstream.