Editor's note: Grass Sea, or Caohai in Chinese, is located at the southeast of Lugu Lake in Sichuan province. It gets its name from the dense reeds covering most of the lake's surface, which make it look like a sea of grass from a distance. One of the most popular attractions in the Grass Sea is the Walking Marriage Bridge. Stretching some 300 meters, the wooden bridge is the only bridge on the Lugu Lake and previously served as a dating place for the Mosuo people. In the daytime, young men and women expressed their interest to each other through dancing and singing. When the night falls, the young men walked for a private date with their beloved women. Walking Marriage Bridge plays an important role in the custom of the walking marriage for the Mosuo people.

Grass Sea (Caohai) scenic spot located at the southeast of Lugu Lake in Sichuan province. Photo taken on Sept. 20, 2018. [Photo by Wan Lina/China.org.cn]

Grass Sea (Caohai) scenic spot located at the southeast of Lugu Lake in Sichuan province. Photo taken on Sept. 20, 2018. [Photo by Wan Lina/China.org.cn]

Grass Sea (Caohai) scenic spot located at the southeast of Lugu Lake in Sichuan province. Photo taken on Sept. 20, 2018. [Photo by Wan Lina/China.org.cn]

Grass Sea (Caohai) scenic spot located at the southeast of Lugu Lake in Sichuan province. Photo taken on Sept. 20, 2018. [Photo by Wan Lina/China.org.cn]

The section of the lake looks like a sea of grass from a distance due to dense reeds. Photo taken on Sept. 20, 2018. [Photo by Wan Lina/China.org.cn]

Tourists enjoy themselves on boats in the Grass Sea on Sept. 20, 2018. [Photo by Wan Lina/China.org.cn]

The section of the lake looks like a sea of grass from a distance due to dense reeds. Photo taken on Sept. 20, 2018. [Photo by Wan Lina/China.org.cn]

The lake is a fertile land for aquatic plants. Photo taken on Sept. 21, 2018. [Photo by Wan Lina/China.org.cn]

Tourists enjoy themselves on boats in the Grass Sea on Sept. 20, 2018. [Photo by Wan Lina/China.org.cn]

A view of the Walking Marriage Bridge on the Grass Sea. Photo taken on Sept. 20, 2018. [Photo by Wan Lina/China.org.cn]