Khar Us Nuur — Black Water Lake — is the second largest freshwater lake in Mongolia, a vast shallow body of water about 50 km east of Khovd in a national park of reed beds and marshes. It is a critical stopover on the Central Asian migratory flyway: pelicans, swans, ducks, and the endangered Dalmatian pelican all use the lake in summer.
The lake is best visited as an overnight trip from Khovd with a guide and 4WD vehicle. There is no resort infrastructure — you camp by the shore or stay in a local ger. Birdwatchers should aim for May or September, when the migratory flocks are largest. Take binoculars and insect repellent; the mosquitoes in summer are extraordinary.