According to the legend, after defeating Ming China, Emperor Lê Lợi was boating on the lake when a Golden Turtle God (Kim Qui) surfaced and asked for his magic sword, Heaven's Will.

Emperor Lợi renamed the lake to commemorate this event from its former name Lục Thủy meaning "Green Water".

The Turtle Tower (Tháp Rùa) standing on a small island near the center of the lake is linked to the legend.

The first name of Hoàn Kiếm lake was Tả Vọng when the Emperor had not given the Magical Sword back to the Golden Turtle God (Cụ Rùa).

Jade Island is connected to the shore by the wooden Thê Húc Bridge, painted vermillion red.