In the imagination of adventure travelers, Papua New Guinea is the last frontier -- a wild place that's so far from the familiar world, it can feel like traveling back in time. So naturally, getting lost in this vast, largely unexplored island has become a rite of passage for any explorers worth their salt. There are hundreds of tribes in PNG, each with their own language and cultural identity. But outsiders beware… Over the past century, these unforgiving jungles have swallowed up some of the world's most accomplished explorers, including Amelia Earhart, who took off from these shores and mysteriously vanished. Bob and Mack visit the remote swamplands that flank one of the world's mightiest rivers to meet a tribe known as the Crocodile Men. The tribe teaches them ancient archery techniques, how to search for crocs with their feet, and invites them to experience firsthand the mysterious healing powers of a local witchdoctor. On the southeastern tip, they race giant war canoes and explore sacred caves that shroud the spoils of cannibal warriors before visiting a remote wildlife sanctuary in the heart of the Coral Sea, where they swim with sharks and wrangle sea turtles -- all in the name of science.