Swan Lake introduction: in the urban area of Copenhagen there is a natural lake area (Serne), divided into five sections by five small bridges, and because there are many swans playing in the lake all year round, so it is also called "Swan Lake". Swan Lake is 6 kilometers long, is a favorite leisure area of Copenhagen people. By the lake, in the sun, in the cool spring breeze, you will see couples hugging each other on benches by the lake, Copenhageners running along the lake in the morning, and two or three friends sharing brunch on the green grass.