Middle Mouse is an uninhabited island situated 1 kilometre off the north coast of Anglesey. It is notable as the northernmost point of Wales. The island measures a maximum of 207 by 110 metres, with a maximum area of 3.7 acres and has a maximum altitude of 16 metres (52 ft) above sea level. It is one of a chain of three islands off the north of Anglesey, the others being Ynys Amlwch and Maen y Bugail.