Hoan Kiem Lake (Vietnamese: H? Ho鄋 Ki?m; meaning 'Lake of the Returned Sword'; also known as H? Guom - Sword Lake) is a lake in the historical center of Hanoi; the capital city of Vietnam. The lake is one of the major scenic spots in the city and serves as a focal point for its public life.

According to legend; emperor L?L?i handed a magic sword called Heaven's Will which brought him victory in his revolt against the Chinese Ming Dynasty back to the Golden Turtle God (Kim Qui) in the lake and hence gave it its present name (the lake was formerly known as Luc Thuy meaning 'Green Water'). The Turtle Tower (Thap R鵤) standing on a small island near the centre of lake is linked to the legend.