In Underworld: Great Britain the team examines the deepest shaft discovered in the UK - Titan. They hope a 3D scan can reveal its true size and secrets about its formation.
In Underworld: Gibraltar, the team learns more about the Rock's caves and tunnels. At Gorham's Cave, secrets are revealed about our Neanderthal cousins and their importance to the Ancient Greeks.
Underworld: Slovenia is an adventure into Slovenia's largest ice cave. The team scans the volume of ice, providing data for scientists to assess climate change.
In Underworld: Belize the team discovers why the Maya Civilization vanished. In the cave of Actun Tunichil Muknal, they uncover the remains of human sacrifices. Professor Holley Moyes reveals how a drought caused the Maya to venture underground to make human sacrifices as they prayed for rains.
Underworld: China uncovers the secrets of China's giant caves. A team maps Cloud Ladder Hall, showing how its size creates an underground weather system.
