Two locations:

Mt. Nantai

Called the "god of mountains," Nantai stands 2,486 meters tall and can be seen for miles around. An active volcano, an eruption of Mt. Nantai in the ancient past is responsible for the creation of the Kanmangafuchi Abyss in Nikko City. Starting in May, adventurous hikers can climb Mt. Nantai, a 7-hour expedition.