S03:E08 - Hollow Victory

Challenger gives the hot air balloon an upgrade that gives it extra lift. The explorers' go along for a test ride, but are sucked into a torrential storm of ionic winds. When the the balloon emerges from the storm cloud, they find themselves below ground level in an underground cavern. Connected to an extinct volcano, this subterranean world is home to new species of dinosaurs, fresh dangers, and a beautiful warrior named Alece. Challenger must find a way to restore the balloon and renew the iron-based fuel supply, while the group tries to survive this hostile environment with limited oxygen.