Follow Steve Backshall as he drops down a sinkhole to explore a series of underground Bornean caves threatened by deforestation and limestone quarrying. The journey may lead to the potential to explore other undiscovered subterranean worlds.
Expedition with Steve Backshall, Wednesday at 10 p.m. on PBS 6.
By submitting your comments, you hereby give AZPM the right to post your comments and potentially use them in any other form of media operated by this institution.