Bruny Island is an island off the south-eastern coast of Tasmania, from which it is separated by the D’Entrecasteaux Channel. Storm Bay is located to the island's northeast. Both the island and the channel are named after French explorer Bruni d'Entrecasteaux. Its traditional Aboriginal name was Alonnah Lunawanna, which survives as the name of two island settlements, Alonnah and Lunawanna.

Geologically, Bruny Island is actually two land masses - North Bruny and South Bruny - that are joined by a long, narrow sandy isthmus. The holiday village of Dennes Point is located in North Bruny, while South Bruny is the site of the towns of Alonnah, Adventure Bay and Lunawanna.

Outside its settlements the island is covered in grazing fields and large tracts of dry eucalyptus forest. Inland forests continue to be logged, but other large sections - mostly along the southeastern coast - are preserved as the South Bruny National Park. While the seaward side of the island features two long beaches - Adventure Bay and Cloudy Bay - it is for the most part extremely rugged, with cliffs of dolerite that are over 200 metres above sea level. Bruny's channel side is far more sheltered and a favourite fishing and recreational boating area for local and interstate visitors.