The Purón is a short limestone stream descending to the coast near Llanes — barely 10 km, but the geology punches above its size. Limestone cobble and bedrock give the river exceptional clarity; even after a summer spate it clears faster than the surrounding slate-fed drainages. The step-pool sequence and confined valley keep gradients steep. Spate events hit hard and recede quickly — the limestone base drains fast rather than sustaining a prolonged rise. On the drop, the pools focus fish. Wading demands respect: polished wet limestone at step lips can be treacherous underfoot.

Wading: Polished wet limestone slabs at step lips