Unsealed: Alien Files - Earth Portals

Seizoen: 3 - Aflevering: 13 / 69 - Eerst uitgezonden: 30 juni 2015 - Episode ID: 1030685

Experts have long believed the universe to be riddled with mysterious portals - shortcuts through space that allow travelers to span vast distances in the blink of an eye. From mighty volcanoes to secret underground civilizations.