The island of Vulcano, situated off the north coast of Sicily, has an active crater which you can hike up to. It is possible to circumvent the crater on a narrow rim, walking through the smoke and the fumes at times, but you have to watch every step to avoid stepping into one of the hot crevices or to slip and slide down into the center of the crater.
None of this kept this courageous teenager from circumventing the volcano on a bicycle.
(Photo by Günter Moser. – Hier geht es zur deutschen Fassung.)