The Afon Aber is a small river in Gwynedd

Gwynedd

Gwynedd is a county in north-west Wales, named after the old Kingdom of Gwynedd. Although the second biggest in terms of geographical area, it is also one of the most sparsely populated...

 that enters Liverpool Bay on the coast of North Wales at Abergwyngregyn

Abergwyngregyn

Abergwyngregyn is a village of historical note in Gwynedd, a county and principal area in Wales. Under its historic name of Aber Garth Celyn it was the seat of Llywelyn ap Gruffudd....

, 53.242°N 4.027°W. It rises in the Carneddau

Carneddau

The Carneddau , are a group of mountains in Snowdonia, Wales. It includes the largest contiguous areas of high ground in Wales and England, as well as six or seven of the highest peaks in the country—the Fourteen Peaks...

 mountains on the northern watersheds of Drum

Drum (Wales)

Drum is a summit in the Carneddau mountains in north Wales, 2 km north-east of Foel-fras. It is 770 m high. It is also known as Carnedd Penyborth-Goch....

, Foel Fras and Garnedd Uchaf

Garnedd Uchaf

Garnedd Uchaf is a minor summit of the Carneddau range in Snowdonia, Wales, and included in the Welsh 3000s. From the summit, distant views to the north can extend as far away towards Ireland and the Isle of Man, whereas to the South, views can extend as far South towards the Berwyn Ranges.It...

 and the eastern watersheds of Drosgl

Drosgl

Drosgl is a summit of the Carneddau range in Snowdonia, Wales, and forms a part of the western Carneddau, also known as the Berau, meaning stacks or ricks.It lies on a ridge heading west from Garnedd Uchaf and Bera Mawr towards Bethesda...

 and Moel Wnion. It is principally noted for the spectacular waterfall of one its principal tributaries, the Aber Falls

Aber Falls

Aber Falls is a waterfall located about two miles south of the village of Abergwyngregyn, Gwynedd, Wales....

, where it leaves the hills and descends in a single drop to the valley floor. The river, joined by the other main tributary, the Afon Anafon, then flows through a densely wooded valley which is now a nature reserve

Nature reserve

A nature reserve is a protected area of importance for wildlife, flora, fauna or features of geological or other special interest, which is reserved and managed for conservation and to provide special opportunities for study or research...

before entering the sea just north of Abergwyngregyn.