River Llynfi
General data
- Name: River Llynfi
- Water system: River Wye
- Water type: River
- Progression: River Wye -> Severn Estuary -> Bristol Channel -> Celtic Sea -> Atlantic Ocean -> Planet Earth
- Climates: Temperate
- Continents: Europe
- Countries: Wales (UK)
The River Llynfi is a short river in the county of Powys, south Wales. A tributary of the River Wye, it runs approximately south to north just to the west of the Black Mountains and partly within the Brecon Beacons National Park.