Vulcanic Gunung Lokon (1580m) contains a simmering crater lake of varying hues. You can hike to it from Tomohon in about three hours, with another hour to reach the peak. However, it's highly active, and it's essential to check out its current status; ask at your hotel. You should also report to the Vulcanology Centre , which is worth a visit in person for its maps and photographs (but the staff does not speak English).
