Mount Roraima is a tabletop mountain standing where Venezuela, Brazil and Guyana meet, the highest of the tepuis, walled on every side by cliffs 400 metres high. There is one weakness in that wall. A natural ramp leans against the cliff on the Venezuelan side. It is the only way up any tepui that does not call for ropes, and it makes this the one people can stand on top of. Getting to the foot of it takes days. The walk starts at the Pemón village of Paraitepui, where the road ends, and crosses open grassland with almost no shade, wading two rivers on the way. Partway across, a rise brings Roraima and its neighbour Kukenán into view together, each cut off by a sheer wall, the clearest look at how abruptly these mountains stand off the plain. The last camps sit under the cliff with the ramp still hidden overhead.
The top is a maze of black sandstone cut into towers and gullies, and rain falls on it almost every day. You sleep in what the guides call hotels: flat dry ground under big overhangs, no walls, only a rock roof, and you wake inside drifting cloud with the stone dripping and nothing visible past it. The same rain gathers in round hollows worn into the sandstone, amber over the dark rock and cold enough to take your breath, and everyone gets in. Rain did the sorting in the Valley of Crystals too, where quartz locked in this two-billion-year-old rock lies loose in clusters, left behind as the softer sandstone wore away around it. Every piece stays where it lies. Cloud covers the summit most of the year and lifts for minutes at a time, long enough for you to see three countries at once. In the Pemón telling this mountain is the stump of a tree that once held every fruit in the world. When it was felled, the water that poured out set the region's rivers on their courses, and that is why they call Roraima the mother of all waters.