Shell Island, also known as Mochras is a tidal island lying west of Llanbedr in Gwynedd, Wales. It is known for its wide variety of shells, and for its wild flowers.
The island is also home to a large campsite which was once a peaceful haven targeted towards families, however in recent years has become quite popular with youths from the West Midlands are and can be somewhat rowdy particularly in peak periods. It's location lies near the extensive Mochras sand dunes. It is said to have been connected to the mythical Lowland Hundred.
During the 'off-season', local farmers bring their sheep from the lowlands to graze on the island.