Dolina Smerty (death valley) is a small area in the upper reaches of Geyzernaya River, where animal carcasses are found from time to time. Place, where most of the deaths occur, is located in the downstream of Zheltyy (yellow) Stream, near its confluence with Krasnyy (red) Stream. That dangerous area is approximately 100x30 meters.
Cold volcanic gases with paralytic effects are coming up from the ground here. The gas paralyses animals that happened to be at the bottom of the ravine. Animals then die of starvation. Paralyzed insects attract small birds and rodents, whose carcasses in turn attract large predators — bears, foxes, wolverines, eagles.
In calm weather toxic gas fills the lower part of the ravine, almost completely displacing oxygen up to 1 meter (and sometimes higher) above the ground. The gas is dangerous to humans as well as animals, although there were no human fatalities.
Death Valley was discovered in the summer of 1975, when Institute of Volcanology employee Vladimir Leonov drew attention to the accumulation of carcasses of bears, foxes, birds and rodents. He then let the staff of Kronotskiy Reserve know. In the Fall of 1975, chief forester of Kronotskiy Reserve, zoologist Vladimir Kalyaev, conducted a full survey of the dangerous area. In 1976 local paper in Kamchatka ran a story, where this site was dubbed the Dolina Smerty (death valley).