The Camddwr is a significant right-bank tributary of the River Towy in the eastern part of Ceredigion, mid Wales. It rises on the undulating plateau east of Garn Gron (52°13′31″N 3°49′29″W / 52.2253°N 3.8247°W) and flows in a generally south-southeasterly direction into Llyn Brianne, a reservoir formed by the damming of the upper Towy, (52°09′27″N 3°45′56″W / 52.1574°N 3.7656°W). A chapel at Soar y mynydd beside the river is often mentioned as being the most isolated in Wales.