The Afon Cothi (also known as the River Cothy) flows through Carmarthenshire in south Wales, making it the largest tributary of the River Tywi. From its source at Blaen Cothi in the north of the county, the river runs south-east before turning south-west, passing through Cwrt-y-cadno, Pumsaint, Abergorlech, and Pont-ar-Gothi before joining the Tywi west of Llanarthney village.

The river is generally regarded as a Grade 3 paddle. The character varies along its length, beginning relatively flat before entering a small gorge with a notable rapid. A commonly paddled lower section of approximately 5km can be completed in around an hour at suitable levels. Paddlers have noted that cutting out a middle section of roughly 10km is an option to avoid a potentially less interesting stretch and to manage daylight hours.

A recommended take-out is approximately 100 metres above Abergorlech bridge, where paddlers can exit and walk up a small side stream to reach the mountain bike trail car park. The river has been paddled at gauge readings around 1.30–1.34, which local contacts have described as appropriate levels. The river is known to hold high levels following significant rainfall, so monitoring gauge readings before putting on is advisable.

One documented hazard is the presence of strainers, which have been noted as a serious concern on this river. Paddlers should be alert to wood and debris, particularly in higher water conditions.

The Cothi is widely noted for its clear water. Under normal conditions the river runs gin-clear, which is a defining characteristic of its appearance, though it will colour up and become turbid when fining down after a spate. The river flows through attractive scenery and is well regarded for its trout and sea trout (sewin) fishing, meaning paddlers may encounter anglers on the water. The combination of clear water, wooded banks, and gorge sections gives the river a distinct character among south Wales paddling destinations.