Beneath The Pennines: The Lancaster Hole

A group of students become trapped inside a mysterious cave where they discover time passes differently underground than on the surface.

A Victorian gentleman hopes to find his long-lost son, who vanished while searching for a mysterious Viking community in a volcanic valley somewhere in uncharted Arctic regions. The gentleman puts together an expedition team to go on the search, but when they reach their destination they must escape from some Viking descendants who will kill to keep their existence a secret.

In 1909, two explorers fight to survive after they're left behind while on a Danish expedition in ice-covered Greenland.

Master diver Frank McGuire has explored the South Pacific's Esa-ala Caves for months. But when his exit is cut off in a flash flood, Frank's team—including 17-year-old son Josh and financier Carl Hurley are forced to radically alter plans. With dwindling supplies, the crew must navigate an underwater labyrinth to make it out.

An Edinburgh professor and assorted colleagues follow an explorer's trail down an extinct Icelandic volcano to the earth's center.