Concierge.com's insider take:
Although roughly a third of the North Island rests upon a geothermal hotbed, known as the Volcanic Plateau, its most active part stretches between the central town of Rotorua in the north and the Tongariro National Park in the south. This territory encompasses more than 100 square miles of volcanic craters, mountains, and lakes; bubbling, steaming, oozing landscapes; and (unfortunate) sulfurous smells. About 17 miles south of Rotorua—smack-dab in the center of the action—is the geothermal preserve of Wai-O-Tapu, or "Sacred Waters" in Maori. Here, you can wander among 4,450 acres of simmering mud pools, surreally crayon-colored lakes and silica terraces. Be sure to see the dazzling gold-edged Champagne Pool and the daily (artificially prompted but still impressive) eruption of the Lady Knox Geyser (State Highway 5, Rotorua; 64-7-366-6333; www.geyserland.co.nz).