Kuang Si is a waterfall in the jungle thirty kilometres from Luang Prabang, in northern Laos, and unlike most famous waterfalls you are allowed to get into this one. Below the main drop the stream steps down a staircase of milky-turquoise basins, each held by a low rim of pale stone, and the lower ones are open for swimming. The water stays cool even at midday, the bed underneath is white, and the current is slow enough to make the widest pools an easy swim. Those rims are not bedrock. The water is full of dissolved lime, and where it meets the air it gives up carbon dioxide and drops that lime along every edge, cementing leaves, moss and grit into porous stone. The barriers rise, breach and rebuild over decades, so the terraces never hold the same shape for long. All of that is the dry half of the year. When the monsoon is in, the same staircase runs brown and too fast to swim, and the turquoise is gone until the rains ease.
A shaded path follows the stream up from the entrance, past smaller cataracts and quiet pools, the canopy keeping the air damp and green long before anything dramatic appears. You pass one basin after another, water spilling from each level into the next. Small wooden bridges arc across the stream between tiers, so you get the whole thing head-on, the pools lined up one behind another below you. At the top of the walk the main cascade comes off a forested cliff in a drop of some sixty metres. The ground trembles faintly there and fine spray drifts back off the water, cooling the air under the trees. The name means roughly deer digging, after an old man who drove his staff into the ground to call up the stream, and the deer that sheltered beside it. On the way back out you pass the last thing you expect at a waterfall: a forest yard of rescued Asiatic black bears, moon bears, named for the pale crescent each one wears across its chest.