Ключевые слова: acidity, akita, bathhouse, bathing, efficacy, fumarole, fumarole hot spring, geothermal, gushing, gushing volume, hachimantai, hell, hell valley, highly acidic, history, hokutoseki, hot spring, hot spring bath, hot spring flowers, hot spring river, hot springs, hot water, hydrochloric acid, japan, japans number one, natural hot spring, nature, radium hot spring, rock bath, rocks, rocky skin, senboku city, spa cure, spa therapy, spring quality, steam, stimulation, sulfur, tamagawa, tamagawa onsen, thermal therapy, virgin forest, volcanic gas, volcano,