Rhymney River

The Rhymney River (Welsh: Afon Rhymni) is a river in the Rhymney Valley, south-east Wales, flowing through Cardiff into the Severn estuary. The river formed the boundary between the historic counties of Glamorgan and Monmouthshire.

The river runs south from its source through (in order) Rhymney, New Tredegar, Bargoed, Ystrad Mynach, Llanbradach (then to the north of Caerphilly), Bedwas, Trethomas, Machen, Draethen, Llanrumney and Rumney (two districts of Cardiff), before joining the Bristol Channel.

The Rhymney Valley (Welsh: Cwm Rhymni) was created as a glacial valley. Sourced within the valley, on the southern edge of the Brecon Beacons, the Rhymney River descends steeply through the town of New Tredegar towards Ystrad Mynach, and then onwards south across a flat plain before entering the Severn Estuary to the east of Cardiff. The villages of Groesfaen, Deri, Pentwyn and Fochriw are located in the Darran Valley and not the Rhymney Valley, which joins the Rhymney Valley at Bargoed.

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