Round Island is an island in Poole Harbour in the English county of Dorset. It lies just off the shore of the Arne Peninsula in the south-west of the harbour, and is separated from the nearby uninhabited Long Island by a narrow channel only a few feet wide.^[1][2]

Round Island
Round Island viewed from the western shore of Poole Harbour
Round Island Location within Dorset
OS grid reference	SY988874
Civil parish	Corfe Castle
District	Purbeck
Shire county	Dorset
Region	South West
Country	England
Sovereign state	United Kingdom
Police	Dorset
Fire	Dorset and Wiltshire
Ambulance	South Western
UK Parliament	South Dorset
List of places UK England Dorset 50°41′10″N 2°00′59″W / 50.686125°N 2.016281°W / 50.686125; -2.016281

The island is 15 acres in size, being a private property with a mix of grassy paddocks and woodland.

Round Island lies within the civil parish of Corfe Castle. The parish was formerly part of the Purbeck local government district,^[1]but now forms part of Dorset Council.