George travels to the northern wilds of Vancouver Island to find out where the rain goes, by exploring the deep, wet caves that pepper the area. Accompanied by a group of hardcore cavers from Alberta and British Columbia, he descends into four different caves that lead deep into the earth. One requires a 40 meter rappel to enter. Another they enter through a waterfall. On a third, the team carries inflatable kayaks into the cave so they can explore the dark river running deep under the ground.