Khorgo-Terkhiin Tsagaan lake National Parkcovers the picturesque Terkhiin Tsagaan lake and the nearby Khorgo Mountain (a recently extinct volcano) in the north central Khangai mountains of Mongolia. The marshes along the west end of the lake are an important breeding and staging area for birds. The park is located in Tariat soum of Arkhangai province.  Khorgo extinct volcano, the symbol of Khorgo-Terkhiin Tsagaan National Park, lies in a huge crater and is covered with deep coloured rocks. Although there is no lake, clouds of steam regularly jet out its crevices and form ice molds in winter, which from a distance look like large flocks of sheep scattered on the mountain. Near the crater, there are dozens of small caverns with stalactites hanging from their ceiling and walls. At some point in the past volcanic lava flooded nearby valleys which are now covered with small woods and offer a great variety of flowers and berries.

A huge lava flow once obstructed the Terkh River, which then resulted in the formation of  Terkhiin Tsagaan Lake. This lake is 16 kilometers long, 20 meters deep, and covers an area of 61 square kilometers. Situated at an altitude of 2.060 meters, the River Suman flows down from this lake in forceful torrents and created a canyon with several small lakes along its path.