Deep

Cavers have ventured deeper into the Earth than anyone has been before.
A Ukrainian team has reached a record depth of 2,080m (6,822ft), passing the elusive 2,000m mark at Krubera, the world's deepest known cave.

Carrying about five tonnes of equipment, they had to negotiate vertical drops and freezing torrents of water. They were also forced to blast rubble from passages that were critically narrowed or blocked by "boulder chokes".

They kept in touch with the surface base camp by rigging nearly 3km (two miles) of rope strung with a telephone wire.

But the August-September expedition encountered many obstacles. By the third week, a sump (cold pond in the cave) blocked the team's downward progress.

Finally, colleagues Denis Kurta and Dmitry Fedotov squeezed through a narrow, 100m-long passage, which successfully bypassed the sump and pointed steeply down.

On 19 October 2004, team leader Yuri Kasjan dropped down a pit and discovered from his altimeter that he had passed 2,000m.

More pits and passages brought the explorers to a sandy chamber at 2,080m, the deepest to date any human has ventured below ground.