The River Cothi is the largest tributary of the River Tywi

River Tywi

With a total length of the River Towy is the longest river flowing entirely within Wales, and is noted for its sea trout and salmon fishing.The river rises within of the Teifi on the lower slopes of Crug Gynan in the Cambrian Mountains and, flowing through the Towy Forest, forms the border...

 in south Wales

Wales

Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...

. It is noted for its trout

Trout

Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

 and sea trout

Brown trout

The brown trout and the sea trout are fish of the same species....

 (sewin) fishing

Fishing

Fishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....

 and for its beautiful scenery.

Dolaucothi

The upper reaches of the river form a steep gorge from which a Roman aqueduct

Roman aqueduct

The Romans constructed numerous aqueducts to serve any large city in their empire, as well as many small towns and industrial sites. The city of Rome had the largest concentration of aqueducts, with water being supplied by eleven aqueducts constructed over a period of about 500 years...

 ran to the gold mines at Dolaucothi. The remains of this leat

Leat

A leat is the name, common in the south and west of England and in Wales, for an artificial watercourse or aqueduct dug into the ground, especially one supplying water to a watermill or its mill pond...

 and others used at the mines to extract the gold

Gold

Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...

 are still visible at many spots along the Cothi and tributaries. The gold mines are owned by the National Trust

National Trust for Places of Historic Interest or Natural Beauty

The National Trust for Places of Historic Interest or Natural Beauty, usually known as the National Trust, is a conservation organisation in England, Wales and Northern Ireland...

, and the mines can be explored underground in guided tours. Many old adit

Adit

An adit is an entrance to an underground mine which is horizontal or nearly horizontal, by which the mine can be entered, drained of water, and ventilated.-Construction:...

s and galleries can be seen in the hillside above Pumsaint

Pumsaint

Pumsaint is a village in Carmarthenshire, Wales situated half way between Llanwrda and Lampeter on the A482 in the valley of the River Cothi. It forms part of the extensive estate of Dolaucothi which is owned by the National Trust....

. 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.