Jiuzhaigou is a tourist attraction with rich natural resources and human landscape, one of the attractions is Changhai. Changhai is one of the core scenic spots in Jiuzhaigou, and one of the beautiful attractions in Jiuzhaigou, known as the "Soul of Jiuzhaigou". Changhai is located in the central area of Jiuzhaigou, the largest sea in Jiuzhaigou. Changhai is bent down the mountain, and his head is hidden deep in the valley of layers. The continuous peaks at the end of Changhai are covered with snow all year round, silver makeup, and the altitude is more than 4,000-5,000 meters. Changhai is also called the mother sea, because Changhai is the largest sea in Jiuzhaigou, although its length is four kilometers, the deepest place can reach 88.8 meters, but its shape is the S-type distribution of the English alphabet, so we can only see about one-third of it. The beauty of the sea lies not only in the color of the lake, but also in the surrounding peaks and forests. The trees on the lakeside are tall and dense, and the peaks are spectacular, forming a natural landscape painting. Especially in autumn, the trees on the lakeside turned golden and red, in sharp contrast to the blue-green of the lake, creating a dreamy scene.