Lake Hovsgol is a freshwater lake located in northern Mongolia near the border with Russia. It is the largest and deepest freshwater lake in Mongolia and is also known as the Blue Pearl of Mongolia. The lake is surrounded by mountains and is located at an elevation of 1,645 meters (5,397 feet) above sea level. It has a length of 136 km (85 miles) and a maximum width of 36.5 km (22.7 miles) and a maximum depth of 262 meters (860 feet).

The lake is fed by over 90 rivers and streams and is a source of the Eg River which eventually flows into the Selenge River. The lake is home to a unique ecosystem with over 60 species of fish, including the endangered Hovsgol grayling, as well as many other species of animals such as bears, moose, wolves, and deer.

The lake and its surrounding areas are also home to several indigenous groups, including the Tsaatan people, who are nomadic reindeer herders. The lake and its surrounding areas are a popular destination for tourists who come to enjoy the natural beauty, go hiking, horse riding, fishing, and bird watching.