Photos and video by renan_ozturk | Scenes from National Geographic's Lost World Expedition—an elevational transect of the Upper Paikwa River Basin, near Guyana’s northwestern border with Brazil and Venezuela, to look for new species of amphibians and reptiles in one of the world’s richest and least explored hot spots of biodiversity. The final section of our transect led us through a pristine, untouched cloud forest, culminating in a first ascent of an unclimbed 7,000-foot (2,100 m) tepui called Weiassipu. After weeks of wet claustrophobia under the jungle canopy, we had reached this hanging ledge system. We were constantly buffeted by a moving river of cloud moisture pouring over the formation, but it cleared for about 30 minutes as we finished setting up the hanging portaledge camp. It was a brief pause in the nonstop nature of the journey, a chance to take it all in. The moonlight illuminated the waterfalls across the basin and the tall tendrils of mist in a 3D show before we were...