As the largest fresh lake in Guizhou, rectangular shaped, Caohai stands 2,200 meters high and is about 20 kilometers wide with 10 kilometers long and surrounded by green mountains. The lake got its name from the various kinds of seaweed growing here. It occupies an area of 200 sq km with vast-stretching wetland full of waterweeds and grass. Rich aquatic plants and mild weather provide birds with an excellent habitat. The black-neck crane, the sole survivor of the world's plateau fowls, usually comes to the Caohai Lake for winter after it breeds in Qinghai Lake. Caohai Lake is one of the best places to bird watch in China, and the WWF has listed it as one of the top 10 bird watching destinations in the world. Up to 100,000 birds winter at the lake between December and March, and 179 different species have been recorded, including protected species, such as the black-neck crane and white storks, golden and imperial eagles, white-tailed sea-eagle, Eurasian crane and white spoonbill.