A team of elite cavers led by 68-year-old explorer Bill Stone are in the depths of Cheve Cave, Mexico. At every step of the way, they use nature’s clues, following the wind and water within the cave, to navigate their next move. Underground it is a maze of twisting tunnels and dead ends in search of a passage that leads to the bottom of the deepest cave on earth.

They have established a chain of underground camps (which took them 30 years to do) leading deeper and deeper into the cave, all the way to the frontline of the exploration (5 km from the entrance).

It takes them around 7-10 days to reach the bottom of the cave, so the leading team gets supplied by multiple supply teams that every so often travel the length of the cave.