Tags: Site Of Special Scientific Interest.
Afon Seiont (Welsh meaning River Seiont in English) is a river in Gwynedd Wales which runs into the Menai Strait.Its source is the outflow of Llyn Padarn near Llanberis and it flows out in a generally northwest direction. Between the outflow and the village of Llanrug it is known as the Afon Rhythallt changing its name just after the village. Its mouth is in the town of Caernarfon forming a natural harbour as it flows out into the Menai Strait.