For the first time, scientists reached the 10.5 metres deep frozen lake at the base of the crater.
Look at amazing pictures from inside the mysterious Yamal crater in Siberia.
A team of scientists managed to go down into the funnel successfully, using climbing equipment on the frozen ground.
This mission to the newly-formed crater on the Yamal Peninsula in northern Siberia is expected to determine the origin and mechanism of this mysterious phenomenon.
Are gas hydrates responsible for underground explosions in the same way as eruptions in the Bermuda Triangle.
Samples and measurements have been done. Data processing will however take many months.
The Yamal crater is about 16.5 metres (60ft) deep. This does not include impact-related rampart at the surface of the hole – add several metres in height. At the base of the cavity lies a frozen lake which is about 10.5 metres (30ft) deep.
This scientific program has been launched by the Russian Centre of Arctic Exploration.