The River Adda is a small watercourse which flows, for the most part culverted, through the city of Bangor North Wales before discharging into the Menai Strait at Porth Penrhyn. The name is said to be of 19th-century origin, deriving from a field Cae Mab Adda (the field of the son af Adam) close to its source. Its earlier name was Tarannon.