Wast Water is a lake located in Wasdale, a valley in the western part of the Lake District National Park, England. The lake is almost 3 miles (4.8 km) long and more than one-third mile (540 m) wide. It is the deepest lake in England at 258 feet, and is owned by the National Trust. It is one of the finest examples of a glacially 'over-deepened' valley. The surface of the lake is about 200 feet above sea level, while its bottom is over 50 feet below sea level.