Afon Artro drains Llyn Cwm Bychan, a rocky, peaty lake high in the Rhinogydd — the roughest, oldest hills in Eryri — and runs only four and a half miles down a steep wooded valley to the sea at Llanbedr and the dunes of Mochras. It is a short, lively spate river off some of the hardest rock in Wales, the water clear, cold and acidic, stained amber where it draws off the bog. It tumbles quickly from the mountain, gathering over a bed of slate, rock and boulder, quick to rise and quick to fall with the rain on the tops. Salmon and sewin — sea trout — run up the Artro into the lake when the water lifts. The character is steep, rocky, wooded freestone on a short, sharp gradient. Wading is boulder-and-slate work, uneven and slick under the trees, and the river is no place to linger when a moorland flood is coming down.

Wading: Slick slate boulders, fast moorland floods

Summer-autumn runs (June–September), primarily nocturnal