Mount Roraima

From the road approaching Paraitepuy on the Venezuelan side, Mount Roraima appears first as a dark flat-topped slab on the horizon, its summit appearing to float above the surrounding jungle like a crashed alien spacecraft, the effect of the surrounding lower tepuis being exactly to create this illusion of impossible altitude.

The hike in from Paraitepuy takes two to three days along a Pemon trail that crosses rivers at ford points that can become impassable after heavy rain, clambers over house-sized boulders, and gradually reveals the true scale of the surrounding tepuis of which Roraima is the highest.

The ascent proper begins at the base of the 400-to-1,000-metre-high cliffs, where a natural staircase of eroded sandstone leads through a narrow gap in the wall and onto the plateau, which is an entirely different world from the lowland forest below, with its own weather system, its own soil and its own species found nowhere else on earth.

The summit of Roraima is a landscape of near-horizontal Proterozoic sandstone layers, deeply fissured by millions of years of tropical weathering, with scattered pools of rainwater, dwarf heath forest growing directly from the rock surface, and rock formations that have inspired legends in the Pemon indigenous culture for centuries.

The cliff edges of the plateau on all sides drop away in near-vertical walls of 400 to 1,000 metres, a feature that gave the tepuis their romantic 19th-century reputation as islands of sky in the imagination of European naturalists and that directly inspired Sir Arthur Conan Doyle's The Lost World.

The border tri-point between Venezuela, Brazil and Guyana sits on the northern edge of the plateau and is marked only by a concrete cairn barely visible among the boulders; reaching it requires a full additional day of navigation across the rocky, boulder-strewn summit and involves crossing international borders on foot without formal checkpoint infrastructure.

Rain on the plateau can be torrential even in the declared dry season, turning the rock surface dangerously slippery and the river crossings flash-flood prone within minutes; the weather on the summit changes within minutes from blazing sun to thick cloud that reduces visibility to a few metres.

The biological significance of Roraima is extraordinary: the plateau has been isolated from the surrounding lowland forest by its vertical cliffs for approximately 70 million years, long enough for unique species to evolve that are found nowhere else on the planet, including pitcher plants, orchids, and several amphibian species.

Mount Roraima is the highest and most iconic of the tepuis, the flat-topped mountains of the Guiana Highlands that inspired Conan Doyle's The Lost World and that represent one of the most spectacular geological formations in South America.

The summit ecosystem is approximately one-third endemic species: plants and animals that have evolved in isolation on the plateau for millions of years and occur nowhere else on earth, trapped on this isolated rock island by the vertical cliffs that prevent colonisation from below.

The multi-day traverse from the Venezuelan side through the summit and optionally to the Brazilian or Guyanese border is one of the great wilderness treks of South America, requiring genuine self-sufficiency and wilderness skills.