Trace the fateful steps that led to the biggest disaster in mountaineering history.

Trace the fateful steps that led to the biggest disaster in mountaineering history.

No one has ever walked without any assistance across Antarctica to the South Pole and back -- until now. We follow two Australian explorers on their excruciating and risky trip to hell and back.

No one has ever walked without any assistance across Antarctica to the South Pole and back -- until now. We follow two Australian explorers on their excruciating and risky trip to hell and back.

A team of shark experts and veteran wildlife filmmaker Andy Casagrande venture off the coast of Gansbaai, South Africa, to Shark Alley on a thrilling mission to capture a great white.

A team of shark experts and veteran wildlife filmmaker Andy Casagrande venture off the coast of Gansbaai, South Africa, to Shark Alley on a thrilling mission to capture a great white.

Join prolific rock climber Alex Honnold on his daring attempt to set a world record by free soloing a trio of harrowing cliffs without any safety lines.

Join prolific rock climber Alex Honnold on his daring attempt to set a world record by free soloing a trio of harrowing cliffs without any safety lines.

Daredevil scientific explorer George Kourounis and his team of climbing experts and scientists set out to tackle one of the world's most dangerous scientific expeditions to date: a descent into Turkmenistan's firey Darvaza crater.

Daredevil scientific explorer George Kourounis and his team of climbing experts and scientists set out to tackle one of the world's most dangerous scientific expeditions to date: a descent into Turkmenistan's firey Darvaza crater.

Nat Geo's veteran bear expert Casey Anderson and seasoned naturalist Jason Matthews plunge into some of the most dangerous bear country in the world, the Alaskan Arctic, determined to collect conclusive DNA evidence and visual footage of a different breed of bear: what they call the Super Bear

Nat Geo's veteran bear expert Casey Anderson and seasoned naturalist Jason Matthews plunge into some of the most dangerous bear country in the world, the Alaskan Arctic, determined to collect conclusive DNA evidence and visual footage of a different breed of bear: what they call the Super Bear