Running roughly north to south, the island is around 600 metres (650 yards) long, and is steep and precipitous along the west coast, rising to a maximum height of 41 metres (135 feet).

There is a cave on the west coast and a natural arch at the northwest of the island.

There are a number of strong tidal races in the area, Tum ba nach is one that extends north from Sheep Island to around halfway across the Sound of Sanda.

As the name suggests, sheep have traditionally been grazed here, however the island is more notable as the primary breeding ground for puffins in the Clyde.

From here the birds are returning to nearby Ailsa Craig, where they were once wiped out.