Crossing frozen tundra, the 15 competing teams and their dogs will endure temperatures of minus 25C or lower.
A dozen out of the 15 teams finished the race which began three weeks ago.
The remarkable annual Beringia dog sled race will go through some of the planet's remotest and most challenging territory in Kamchatka.
The world famous traveller made call ahead of his latest epic adventure by dog sled to Greeland via the North Pole.
Valuable obsidian travelled during Early Holocene times from Lake Krasnoe in Chukotka to Zhokhov Island deep in the Arctic.