Fierce Earth

The team travels to Morocco, North Africa, and visits the Sahara Desert. Leo Houdling is put to the test when he discovers how to escape the grip of quicksand, and Dougal Jerram explores how sand can be a powerful and destructive force for those living in the area. Meanwhile, Leah Gooding meets the children who roam the desert.

American storm chaser Mike Theiss reveals how Boston came to a standstill after a blizzard in 2013, and Leo investigates the effect of wind chill in one of the UK's most extreme wind tunnels.

The team discovers the secrets of ice, as Leo Houlding learns about the properties of the substance on a bobsleigh in the Swiss Alps. Mike Theiss witnesses the devastating power of ice storms in eastern America, and Clare Nasir and Dougal Jerram reveal how glaciers are formed.

The team travels 6,000 miles to Chile to visit the Atacama Desert - the driest place on Earth. Leo Houlding sky dives out of a plane to reveal why the air is so dry, and Clare Nasir discovers an ingenious way of finding water.

The team travels the length of India tracking the monsoon as it passes over the country to the village reputed to be the wettest place in the world. Leah Gooding reveals how the locals deal with the rain, while Dougal Jerram abseils down a large waterfall and explores the huge cave systems created by the torrential downpours.

The team travels to the French town of Tignes in the Alps, where Clare Nasir and Dougal Jerram go skiing and learn about the threat posed by avalanches. They also test out the latest survival technology.

The team explores the threat of landslides in the UK as Leah Gooding travels to the Isle of Wight to find out why it is under constant threat from erosion. Plus, Dougal Jerram explores the biggest sinkhole in Britain.

The team travels to Iceland - a country created by volcanos. Dougal Jerram dives into the sea to touch the tectonic plates of Europe and America, while Leo Houlding explores the power of a geyser.

The team explores the power of the sea as Leo Houlding and Claire Nasir travel to Santa Cruz, California, to participate in a surfing lesson. Leah Gooding experiences a fast-rising tide in the Isle of Sully, and Dougal Jerram helps to guide a supersized ship into one of the UK's busiest ports.

Leo Houlding looks back over his top ten fierce moments, from freezing blizzards to boiling hot deserts. Plus, a look at the number one challenge which pushed him to his limits.