The tepuis in South America, often called "islands in the sky" for their sheer cliffs and flat tops towering 10,000 feet above the jungle floor, create isolated environments that make these unique land formations evolutionary islands.There are unique species living on the tops of these mountains that exist nowhere else in the world. Often compared to the Galápagos Islands for being an ancient island chain with a stunning array of biodiversity, the tepuis are actually much older. While the Galápagos are thought to be around five million years old, it is estimated that the tepuis have been rising up for the past 20 to 40 million years, making them the oldest "islands" in the world. Climber Mark Synnott first set his sights on climbing the tepuis when he read an article about their unique biodiversity in National Geographic magazine and wondered if he might be able to offer his climbing skills to assist scientists in the exploration of their sheer cliffs. Teaming up with Bruce Means, an ecologist studying the diversity of life on the tepuis, Synnott helps find a new frog species and encounters some challenging climbing conditions along the way.