Mary Island () is located off the Kimberley coast of Western Australia.
It is in Vansittart Bay in the Cape Bouganville Aboriginal Reserve, between Admiralty Gulf and Napier Broome Bay.
The island has a tropical savanna climate (Köppen: Aw); with a short wet season from December to mid-April and a long dry season from mid-April to November. Climate data was sourced from the nearest weather station at the Mungalalu Truscott Airbase on the mainland. Extreme temperatures ranged from on 28 October 2018 to on 11 July 2007. The wettest recorded day was 16 March 2005 with of rainfall.