The Legend of the Turle and the Sword
Hoan Kiem Lake (Lake of the Returned Sword) - According to the legend, emperor Lê Lợi 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"). (From wikipedia)