Auckland has nearly 50 volcanic cones in and around the city, and Rangitoto is the largest and youngest at 600 years old. Reachable by a 25-minute ferry from downtown, its symmetrical cone is visible from some parts of the city. Once on the island, it's a one-hour hike to the summit, with lava caves along the way and panoramic views from the top. If you're not up for the climb, four-wheel drive road-train tours are led by ranger guides knowledgeable on the geology and history of the island. Ferries run several times a day, with on-island tours twice daily; book in advance.