It was named after the Duke of Portland by Matthew Flinders during his 1798 circumnavigation of the island in the sloop Norfolk with George Bass.

[2] Banks Strait separates Cape Portland from Clarke Island, one of the Furneaux Group, to the north.

[3][4] Cape Portland Post Office opened on 6 April 1865 (first as a receiving house) and finally closed in 1918.

This area supports more than 1% of the world population of the Cape Barren goose, chestnut teal and the near threatened hooded plover.

It also occasionally supports large numbers of pied oystercatchers, double-banded plovers and breeding fairy terns.