| Site of Special Scientific Interest | |
| Location | Carmarthenshire |
|---|---|
| Grid reference | SN4887214850 |
| Coordinates | 51°48′42″N4°11′37″W / 51.811796°N 4.1936935°W |
| Interest | Biological |
| Area | 15.82 ha |
| Notification | 24 July 1987 |
Ynys Uchaf is a section of floodplain of the River Gwendraeth that is a Site of Special Scientific Interest in Carmarthen & Dinefwr, Wales.