Vallée de Mai Nature Reserve

Descending the stone steps into the valley feels like stepping into a living museum of tropical evolution, where the air is thick with humidity and the canopy closes overhead until the light filtering through turns green and amber.

The coco de mer palms — the only place on earth where they grow wild at scale — tower to thirty metres or more, their massive fronds creating a perpetual rustling that is the valley's constant background sound, a sound that tells you this forest has been here for a very long time.

The forest floor is carpeted with the fallen husks and fronds of the palms, and the roots of the trees themselves emerge from the ground in vast stilt-like buttresses, engineered by evolution over millions of years to anchor the trees in the thin volcanic soil.

The Seychelles black parrot, one of the rarest parrots in the world and found only in the Seychelles, is present in the valley but elusive; you are more likely to hear its distinctive squawk from deep in the canopy than see it clearly, and your best chance of a sighting is early morning when the birds come to drink at the forest pools.

The undergrowth is dense with other endemic palms — Lodoicea maldivica dominates the canopy but the valley shelters all six of Seychelles' endemic palm species, a concentration of endemism that is remarkable for such a small area and makes this forest globally significant beyond its iconic seeds.

Rainfall in the valley is high — around 2,400 millimetres per year — and the palms have evolved to capture and channel every drop, the funnel-shaped bases of their giant fronds directing water down the trunk and into the root zone, a natural irrigation system that sustains the forest through the dry season.

The double coconut or coco de mer produces the largest seed in the plant kingdom, sometimes weighing over twenty kilograms, and the shape of the seed — two fused lobes resembling a woman's hips — gave rise to legends in the ancient world about trees growing beneath the sea, with palm fronds visible above the waterline.

Guided walks in the valley reveal the scale and complexity of this ecosystem, with knowledgeable local guides able to point out the distinctive silhouette of each endemic tree species and explain the intricate relationships between the forest's pollinators, seed dispersers and the plants that depend on them.

It is the only place on earth where the coco de mer palm grows wild at scale, and the forest it creates is a prehistoric-feeling environment that exists nowhere else.

The valley shelters all six of Seychelles' endemic palm species in a small area, a concentration of botanical endemism found almost nowhere else in the world.

It is a UNESCO World Heritage Site — the first in Seychelles — recognised for its outstanding universal value as a unique forest ecosystem.