More than 50 islands lie in the Hauraki Gulf, forming the Hauraki Gulf Marine Park, administered by the Department of Conservation. Many of the islands are nature reserves, habitat to rare plants and birds, and public access to these is limited. Others are public reserves that can be arrived at by ferryboat, and a few are privately owned.

Great Barrier Island, the biggest in the gulf, has a population of around 1,100, and is mainly agricultural. Motuihe, a well-liked swimming spot, was a prisoner-of-war encampment during World War I and the sight of a daring escape: Count Felix Von Luckner, famous for the "Sea Devil," commandeered the camp commander's boat and got as far as the Kermadec Islands before being recaptured.

You can observe exceptional native birds up close at Tiritiri Matangi, a bird sanctuary open to the public. A gentle stroll on well-maintained and signposted paths takes you to the top of the island and the oldest lighthouse in the gulf, still in function. The island is, free from predators, and the birds are fearless.