When Mt. Tarawera erupted in 1886, destroying Rotomahana's terraces, not all was lost. A volcanic valley emerged from the ashes, extending southwest from Lake Rotomahana. It's consequently one of the world's newest thermal-activity areas, encompassing the boiling water of the massive Inferno Crater, plus steaming cliffs, bubbling springs, and bush-fringed terraces. A path (one–two hours) runs through the valley down to the lake, where a shuttle bus can get you back to the entrance. Or add on a lake cruise as well. Waimangu is 26 km (16 mi) southeast of Rotorua; take Highway 5 south (Taupo direction) and look for the turn after 19 km (12 mi).