The Cobourg Peninsula is located 350 km east of Darwin in the Northern Territory, Australia. It is deeply indented with coves and bays, covers a land area of about 2,100 km², and is virtually uninhabited with a population ranging from about 20 to 30 in five family outstations, but without any notable settlement or village. It is separated from Croker Island in the east by Bowen Strait, which is 2.5 km wide in the south and up to 7 km in the north, and 8.5 km long. In the west, it is separated from Melville Island by Dundas Strait. From Cape Don, the western point of the peninsula, to Soldier Point in the east of Melville Island, the distance is 28 km. In the north is the Arafura Sea, and in the south the Van Diemen Gulf. The highest elevation is Mount Roe in the south with an altitude of 160 m.
All of Cobourg Peninsula is part of Garig Gunak Barlu National Park, which also encompasses a few nearshore islands. Mostly a tourist attraction, it is known for its pristine wilderness. It is home to a large variety of sea life and the world's largest herd of pure-strain banteng. It is also renowned for its Aboriginal culture. While it is only sparsely inhabited today, it was once the site of two failed attempts at founding a major trading port on its northern shores, Fort Wellington at Raffles Bay (1827-1829) and Fort Victoria at Port Essington (1838-1849), of which the ruins are still accessible today.