Mochras (also known in English as Shell Island) is a peninsula lying west of Llanbedr in Gwynedd, Wales.

The peninsula was formed after the River Artro was diverted by the Earl of Winchilsea in 1819 from its previous course where it entered the sea to the south of Mochras.

The area consists of a low lying raised beach (which encompasses the nearby Llanbedr Airport).

[3] Public vehicular access to the peninsula is only possible via a causeway across the estuary of the River Artro when the tide is out.

Access on foot is always possible from the adjacent Morfa Dyffryn beach, which extends for several kilometres south of Mochras.