As lakes go its big, how big ? 136km long, 36.5km wide 262 meters deep, but at 1560m altitude it’s a big bowl of water in the sky ! It is possible to scubadive it take a look at this article http://www.divernet.com/Travel_Features/far_east/220400/mongolias_dark_blue_pearl.html
Otherwise you can visit the reindeer people who live is wigwam style tents towards the Russian border, fish for massive lake salmon (Taiman). This is a very scenic part of the world and makes for some excellent horse trekking.
Mongolia’s lakes (notably the huge Khuvsgul Nuur) represent another good hiking destination, as do the Four Holy Peaks surrounding Ulaanbaatar or the Gobi Gurvansaikhan National Park, in the South Gobi. Visitors should note that the weather, although milder than expected, can vary greatly, especially in the mountains and in the Gobi Desert; it is recommended to bring a warm sweater and raincoat for any time of the year.
