Tumpak Sewu is a semicircular cliff in East Java, Indonesia, 120 metres high, with dozens of separate streams coming over it at once, side by side, all the way around the curve. Its name means a thousand waterfalls, and the plural is the point. The rock is columnar basalt, old lava off Semeru, the highest volcano in Java, and the Glidik river has cut a horseshoe-shaped box canyon into it. The water never settled into a single notch: it seeps and spills along the whole rim, arriving as a braided curtain rather than one fall, and the canyon walls stay green on spray alone. The classic view is from the Panorama deck on the Lumajang rim, ten minutes' walk from the gate, where the fan shows its whole width, with the cone of Semeru behind the ridgeline above it. That view has a clock on it. Cloud builds over the canyon by mid-morning and can cover the falls completely.
The way to the bottom goes down the cliff itself. Bamboo steps, handrails and short roped sections drop through the jungle for thirty to forty-five minutes, past clearings half-screened by palm fronds where the curtain shows at a different angle each time. At the floor you wade the shallow Glidik to the mouth of the amphitheatre. What looked like lace from the rim now comes down to your left and your right as well as ahead, loud enough to end conversation, and nobody stays dry. Twenty minutes further down the gorge is Goa Tetes, quieter and stranger. Smaller cascades run there over rock stained rust-orange by mineral springs seeping out of the cliff, which lay down soft travertine ledges you can duck under and have hollowed shallow caves behind them. The floor can only be reached in the dry months, roughly April to October. The rains lift the river too fast to wade and take the ladders and steps out with them; when the water drops they have been rebuilt, and the way down is never quite the one before.