What are dark, creepy and super weird?! Caves! So Charlie and Kirby are setting out to explore these fascinating rock formations. To do that, they're heading to Virginia to meet up with a caving guide who will take them on an amazing underground expedition to explore a massive maze of tunnels and passageways.

Originally released by National Geographic, 2017. Streaming video file encoded with permission for digital streaming by Infobase on January 05, 2023.