We spend so much time exploring the oceans, skies and land that we rarely stop to consider what's under our feet. What great possibilities for exploration still remain underground? Well on the island of Sumba, Indonesia, quite a lot. Join Hamzah, Galih, Ino, Ginting and Akbar as they strap in to head underground and discover the secrets of a new cave system. Going Underground | Exploring A Colossal Cave On The Isle Of Sumba