At the northern tip of Dianchi Lake, where the city meets the water, Caohai ("Grass Sea") is a 17-square-kilometre wetland park of reed beds, lily pools, and shallow open water — the surviving wild edge of what was once a much larger lake. It is one of the most important wintering grounds in southwest China for migratory waterfowl: black-headed gulls, ducks, herons, and several rare species of grebe gather here in numbers from November to March.
Wooden boardwalks and viewing pavilions run through the reed beds, and a small visitor centre at the entrance has telescopes you can borrow. The wetland is a quiet corner of the city even on weekends. Bus 24 from central Kunming or a fifteen-minute taxi gets you here. Best at dawn for birds, late afternoon for light.