Wast Water or Wastwater () is a lake located in Wasdale, a valley in the western part of the Lake District National Park, England. The lake is almost long and more than wide. It is a glacial lake, formed in a glacially 'over-deepened' valley. It is the deepest lake in EnglandThe Lake District National Park Authority at . The surface of the lake is about above sea level, while its bottom is over below sea level. It is owned by the National Trust.
