The River Taff is 64 km long and is formed at Cefn-coed-y-cymmer in Merthyr Tydfil at the confluence of the rivers Taf Fechan and Taf Fawr.
The river flows from the north to the south of the city, entering Cardiff at Taffs Well and flowing south through Forest Farm, Hailey Park and Bute Park, then on through the city into Cardiff Bay.
In the mid-1800s, Isambard Kingdom Brunel came up with plans to divert the River Taff to the west, away from its old course around Cardiff Castle. The river now flows next to Cardiff Arms Park and the Principality Stadium. It also allowed Cardiff Central Station to be built in an area that had previously been prone to flooding.
The River Taff used to be heavily polluted by industry along its banks. In recent years, the water quality has improved and it is becoming one of the best rivers for salmon and trout in Wales
The river is important for migratory fish, otters, wildfowl and bankside vegetation and acts as a major wildlife corridor. Bats, otters, Atlantic Salmon, Trout, Grass Snakes and Kingfishers are amongst the diverse species recorded in and around the River Taff SINC (Site of Importance for Nature Conservation).