[1] The head of the peninsula is Cape Brett itself (also known by the Māori, Rākaumangamanga), a promontory which extends north into the Pacific Ocean at the eastern end of the Bay of Islands.

A noted landmark, the natural arch "Hole in the Rock" of Piercy Island lies about 500 metres off the cape.

The peninsula includes Opourua/Oke Bay, off Rawhiti Road, about 29 km from Russell.

[4] A 4.2 km (2.6 mi) walking track runs from the Tangatapu wetlands over a ridge with regenerating coastal forest to a sandy beach at the head of the harbour, near the whaling station.

Photos of Whangamumu Harbour - whaling station in 1927, 1962 aerial view