The River Cothi is the largest tributary of the River Tywi in south Wales. It is noted for its trout and sea trout (sewin) fishing and for its beautiful scenery.
The upper reaches of the river form a steep gorge from which a Roman aqueduct ran to the gold mines at Dolaucothi. The remains of this leat and others used at the mines to extract the gold are still visible at many spots along the Cothi and tributaries. The gold mines are owned by the National Trust, and the mines can be explored underground in guided tours. Many old adits and galleries can be seen in the hillside above Pumsaint. The aqueducts fed many large tanks perched on the hills above the mine, and were used to prospect for the gold veins, as well as sweep away the waste overburden during opencast mining prior to underground working.
Coordinates: 51°52′N 4°11′W / 51.867°N 4.183°W