Board the ferry in downtown Auckland for the scenic 75-minute trip across the Hauraki Gulf to Rotoroa Island, one of a chain of islets off the east coast of Waiheke.
For more than a century, the island was an alcohol rehabilitation center operated by the Salvation Army. You can visit heritage buildings from the center, including the chapel, jail house, and community gardens. Learn how it was New Zealand's first and longest-running addiction treatment center in a state-of-the-art museum, which also features displays about Rotoroa's Maori and European history.
You can also soak up the outdoors at four sandy beaches, perfect for picnics and swimming. Take a walk along groomed trails to admire a large outdoor sculpture by artist Chris Booth, located on the island's southern headland. History buffs might carve out some time to see the island's cemetery, which overlooks the Hauraki Gulf and Ponui Island. And if you like to fish, cast a line from the wharf at Home Bay, or from the shore at other inlets.
As you walk around, note your natural surroundings. The Rotoroa Island Trust has teamed up with the Auckland Zoo to create a wildlife sanctuary for up to 20 endangered native animals including kiwi birds, lizards, and geckos. You'll also spot a variety of native plants taking root along the trails thanks to the trust's revegetation project.
Expect to have about six hours to explore the island on your own before the return ferry to Auckland departs in the afternoon.