The island is just 200 yards long and rises to a height of 89 feet. There is a cave on the shoreline at the north. A drying reef surrounds the island to the north and east. More of these dangerous reefs litter the sound between Glunimore, Sanda and Sheep Island. Paterson's Rock is yet another dangerous rock around a mile to the east. Despite these obstacles the natural harbour formed by the three islands is still often used by boats rounding the Mull of Kintyre.
Glunimore and neighbouring Sheep Island are the most important breeding grounds of puffins in the Clyde and the birds are now returning from here to Ailsa Craig another traditional breeding ground. Guillemots and Razorbills also nest here.
The island was the subject of a report by two naturalists who visited in 1899 performing a survey for the Natural History Society of Glasgow.