The Rhymney River is a river in the Rhymney Valley, south Wales, flowing into the Bristol Channel.
The river forms the border between the traditional counties of Glamorgan and Monmouthshire.
Path of the river
The river runs south, through (in order):
Being part of the South Wales coal and iron producing area, the river had poor water quality through most of the twentieth century. Since that time, the water has become a lot cleaner.