Known as “The Dark Blue Pearl”, Lake Khovsgol is Mongolia’s largest and deepest lake. Located in the northernmost province, it is the largest tributary stream of Lake Baikal in Russia. Lake Khuvsgul is 136 km long, 36 km wide and 262 metres deep and is located at an altitude of 1645 m above sea level and is frozen from January until April or May. It's the second largest fresh water lake in Central Asia. It's inhabited by nine species of fish including the Siberian grayling and lenok. Fishing and sport fishing are becoming popular in the lake area. Taiga Fauna and Flora,Tsatan, practicing raindeer breeding are the main attractions for tourist. A ferryboat operates between Khatgal and Khanh, two towns on the southern and northen shores of the lake that is within the boundaries of the Khovsgol National Park.  Different ethnic groups live in the area: Khalh, Darhadt, Butyat. Tsaatans are raindeer herders. Lake Khovsgol is on the important migration route for birds from Siberia, thus facilitating marvelous opportunities for birdwatching. This lake has a volume of 380 km3 and it is second in Asia and 14th largest in the world. Khuvsgul Lake contains 93.6 % of total surface fresh water of Mongolia and 1% of world fresh water. Khuvsgul Lake is surrounded by beautiful high mountains of the Khoridol Saridag and Bayan Mountain Ranges, along the west shore. Many mountain rivers flow into this lake including 17 rivers flowing during the whole year. Flat-topped mountains with sloping mountainsides, covered by forests, lie on the east shore of the lake and those mountains are sources of 29 rivers flowing into Khuvsgul Lake.

The Munkh Saridag Mountain Range, the highest mountains in Khuvsgul province, are along the north shore of this lake. South part of Khuvsgul Lake becomes narrow and the Eg River starts out here. Drainage basin of the lake is 5,300 sq km that holds 46 rivers and streams. 69% of South side of Khuvsgul Lake is deeper than 100 m.
The lake water is coldest in Mongolia, with +18 Celsius of water surface in summer, because of its deepness. It starts to freeze in September but completely covered by 1.0-1.5 m thick ice in November while it starts to melt in May but sometimes it keeps its ice until beginning of July. Water visibility is up to 22.9 m in the middle, but it is 14.3 m near the shore.

There are 4 islands namely Modon Khui, Khadan Khui, Dalain Khui and Baga Khui. From these, the largest one is Dalain Khui Island with a 5.8 sq km area, 70 km from north shore. Nine species of fish inhabit Khuvsgul including omul, herring, lenok, grayling, perch and roach.  This area has been protected since 1992 as a National Park. The lake is still being used for transportation. Russian merchants started using boats for transportation in 1913.