Mount Adatara, Volcanic summit in Fukushima Prefecture, Japan

Mount Adatara is a stratovolcano whose highest summit, Minowa-yama, reaches 1,728 m; the Adatara range stretches about 9 km north to south. Its rounded, snow-streaked peaks rise above dark wooded lower slopes and a flat plain. The summit area holds the Numanotaira crater, hot springs and fumaroles.

Mount Adatara is a compound stratovolcano whose main body, from Minowa-yama to Osho-san, formed around 250,000 years ago; the summit cone grew in a later phase from about 120,000 years ago. Sulfur was mined on the western slope until the 1960s, and the Banda Express Railway carried the ore from Numanohira Station, reached by cableway. On 17 July 1900 a steam eruption at the Numanodaira crater destroyed the sulfur refinery and killed 72 workers, injuring 10.

The mountain appears in the Man'yōshū, and Kōtarō Takamura's Chieko-sho, in the sections "Two Under a Tree" and "Innocent Talk", names it as "Atatara-yama". Kyūya Fukada included it in his essay collection Nihon Hyakumeizan. The painter Kaii Higashiyama based his work "Blue Echo" on the beech forest near the old Tsuchiyu Pass, one of the mountain's trailheads.

The Okudake trailhead in the Adatara Kogen ski area is the shortest approach: the Adatara Mountain Ropeway runs from Okudake to Yakushi-dake at about 1,300 m, cutting the climb to the main summit to roughly 2.5 hours. The Kurogane-goya mountain hut, open year-round and fed by its own hot spring, sits on the route via Mine-no-tsuji; it closed on 1 April 2023 for renovation. Above the treeline there is no shelter, so avoid the ridge in thunderstorms or poor visibility.

Active fumaroles and hot springs exist within the summit crater, showing that the mountain remains geologically active today. These steaming vents and warm water are visible signs of ongoing volcanic processes beneath the surface.