Satellites show giant hole ringed by 20 'baby craters'.
Fear that thawing permafrost caused damage to storage tank.
International researchers have gleaned these extraordinary hidden scientific secrets by drilling 318 metres into a unique lake in northeastern Siberia.
Radiation, chemical and biological forces tackle two million tonnes of toxic chemical waste with huge mercury stockpile and oil poisons.
Both Greenpeace and the World Wildlife Fund are expressing grave concern at the risk of contamination in the Pechora Sea.
Can the world's oldest and deepest lake finally realise its potential as a world class venue?