Lake Khuvsgal is one of the biggest lakes on earth. It also flows into the world's largest freshwater lake, Baikal, in Russia.
But this vital resource is under threat. Dozens of vehicles have fallen through its ice since the 1950s.
"One of the trucks fell half-way through the ice. The other sank 45 metres. One of our divers went under the ice and connected the cable to pull it out. The other truck had a body inside," Tengis Boldbaatar, the Khuvgul National Emergency Management Agency Sergeant Coast Guard said.
Some vehicles, however, are still submerged, and are believed to contain fuel that may contaminate the water. Experts warn if they leak, the consequences would be catastrophic.
Grace Brown reports from Khuvsgal.