Boris Fyodorov, 37, complains it was 'too warm', and now wants to try in minus 60C.
Swimming 1km, in the middle of the winter, in Siberia, at water temperature of zero Celsius and air temperature below -30C.
Reindeer herders find more craters in the far north in a deepening puzzle for scientists.
Satellites show giant hole ringed by 20 'baby craters'.
Mysterious 'gigantic' hole in remote region spotted by helicopters over gas-rich Yamal peninsula.
Putin fires top official in Russian Far East, and calls for Investigative Committee to check how authorities performing.
Norilsk is home to the world biggest mining and metallurgy complex, and is shut off from the world in more ways than one.