The geography of Tomohon is located in the Asian portion of the Pacific Ring of Fire, flanked by two active volcanoes, those are Mount Lokon () and Mount Mahawu (). The area is mostly made of young volcanic rock, with a composition of andesitic and basaltic tuff, and is of a brittle nature and easily eroded. The material component of the volcanic eruption with a cool temperature increase the fertile soil, and for the people taking advantage to produces fruits, vegetables, and flowers. In the southern, there's a Lake Linow, a naturally formed crater from volcanic eruption. Around the lake, there are various geothermal manifestation such as hot springs, fumarole, and also mud pool.