Erawan Falls is a waterfall of seven tiers climbing a forested hillside in Kanchanaburi province, in western Thailand, and each tier holds a pool of milky emerald water you can get into. The rims holding those pools are travertine, stone the stream lays down for itself out of the lime it carries, so every level sits behind a low dam of its own making. The water comes off the limestone above and stays cool even at midday. You lower yourself in, then sit on a ledge worn round by the current with the next cascade pouring in beside you. Where a tier comes down in a broad curtain you can stand under it for a cold shower that drums on your shoulders. The small fish crowding your feet are garra, the doctor fish of fish-spa foot baths, here living wild. They gather thickest around anyone standing still, and scatter the moment you move.
The lower tiers are the crowded ones, and they belong to the macaques. A troop works the water's edge and the branches over it, wild and entirely used to people, and anything left unwatched is theirs. The path up is about two kilometres. Above the paved lower section it turns into a proper forest scramble, steeper and rougher with every level. What changes as you climb is not only the walking. The canopy closes in, the roar of the lower falls softens to a rush, hornbill calls come down through the trees, and the pools get clearer and emptier. The seventh tier is the quiet one at the top. Its fall comes over a lip that Thais read as the head of Erawan, the three-headed white elephant the god Indra rides across the sky. A white elephant is a royal, near-sacred animal here; one of them rode the flag of old Siam. The waterfall is named for that head, and it is the one thing in the park you cannot see without climbing all seven tiers.