Quanwan, also known as Nayu, is a tidal marshland, located in the southwest of Qinghai Lake, with wet plants, lichen grass, flat spike grass, fir leaf algae and so on. There are many spring water gushing to form a marsh wetland. It is a large number of migratory birds, travel bird breeding areas and habitats. Large swans and black-necked cranes and other rare birds live here. There are very few people visiting Quanwan, and no one will usually come in summer because the tidal flat wetlands here are difficult to get close. Visitors come to watch the big swans in winter, because this winter is not frozen, so the swans gather here. The big swans in the morning mist steam are very beautiful at sunrise.