Mahawu is the northernmost of a string of "young" volcanoes along the spine of North Sulawesi. Less active than it's neighbors, Mahawu is just a few minutes' drive from the center of Tomohon. A small road leads to a visitors center about halfway up the side of the crater. From the small parking lot, you have to hike up to the rim. There is no paved path or stairs, just a rough cut trail through small brush and thickets of elephant grass that took me about 20 to 30 minutes.
The crater of Mahawu Volcano near Tomohon
You reach the rim of the 180 meter wide crater on the south side. From the rim, it's a 140 meter drop almost straight down to the floor of the crater, where there are a couple of muddy lakes and a few smoking fumeroles. If you hike around the rim, through more thickets of elephant grass, to the north side, you will get a good view of Manado city and the Bunaken Marine Park islands, if the weather permits of course.
There is no set fee to visit Mahawu, but a small donation to the visitors center will get a tree planted in your name in the growing forest around the base of the volcano. Manado-based Safari Tours can arrange a tours to Mahawu Volcano.