INTO THE LOST WORLD

Deep in the jungles of Guyana, dramatic sandstone mesas called tepuis thrust vertically through the dense foliage, creating high plateaus above the canopy that are home to many plant and animal species found nowhere else on Earth. Little is known of the plants and animals that inhabit the difficult-to-access cliff walls. Here you can find some of the last great places on Earth that are largely untouched and very challenging to explore. National Geographic Ultimate Explorer correspondent Mireya Mayor joins a team of scientists and climbers, including Ultimate Explorer field specialist Jesús Rivas, on a journey to explore these cliffs in search of new plant and animal species. Their destination is Mount Roraima, the country's tallest tepui, located at the border of Guyana, Brazil and Venezuela. But the team's approach is an arduous month-long jungle adventure filled with challenges - including torrential rains, malaria and a dwindling supply of food. And once they arrive, the dangerous task of collecting plants and animals from the tepui's sheer rock face begins. It is a high-risk endeavor, but the scientific payoff - the discovery of new species - could be tremendous. The adventure does not end there. During the journey, Mireya undertakes her first rock climb outside the classroom - a daring descent 250 feet into a virtually unexplored sinkhole on top of Roraima's neighbor, Mount Weiassipu. Join Ultimate Explorer for this extreme adventure into the unknown and see if Mayor and her team have what it takes to withstand the challenges of Guyana's untamed wilderness.