In Guatemala, archaeologists identify an ancient site containing a series of unknown structures; a lake full of jellyfish is studied on a remote South Pacific island; Argentinian researchers discover a complex that may have a dark past.

In the rain forests of Belize, researchers find a bizarre skeleton deep underground in a mysterious cave; an ancient city is discovered on a remote plateau in Cambodia; a strange coin is unearthed on the Wessel Islands of Australia.

On the island of Madagascar, paleontologists discover an intact fossil unlike any known animal, living or extinct. Also, bizarre stone spheres are discovered in Costa Rica and the curious remains of a small man are found in Chiapas, Mexico.

In the tropical lowlands of Northern Colombia, a team of scientists discover a massive, unidentified animal vertebra; dozens of jars packed with bones are uncovered in Cambodia; a strange rusted vehicle is found on the small island of Peleliu.

In the remote Cagayan Valley of the Philippines, archaeologists discover the remains of an ancient rhinoceros; a Brazilian island is infested with thousands of deadly vipers; researchers uncover shocking human remains deep in a Kenyan cave.

On the island of Pohnpei in Micronesia, explorers discover ancient structures hidden beneath dense vegetation; a strange glowing forest is discovered in India; an immense tunnel system is investigated in the Brazilian jungle.