Veryovkina Cave, the deepest known cave on Earth ... The air pressure is 10% higher than at the surface, and temperatures hover at a frigid 39°F (4°C), making hypothermia a constant danger.

Probing a series of “windows” in the walls of the deepest part of the cave, the team was blocked time and again by sumps or impossibly tight squeezes. But finally, on October 19, Kasjan ...

Also known as Voronya Cave, Krubera is the second-deepest known cave on Earth - it was previously believed to be the deepest cave in the world before this honour was switched to its neighbour ...

Krubera Cave in the republic of Georgia is currently the deepest known cave, at 7,208 feet. But Dark Star, with so many areas still to survey, is a prime candidate to take over the title.

BEST OF 2019: The Veryovkina Cave is the deepest known cave on Earth. It took half a century and about 30 expeditions for Russian cave explorers to reach its record depth of 2,212 metres.