Living in the shadows of active volcanoes is like sitting on a time bomb, especially when one of them is called Fire Mountain or Gunung Merapi in Indonesian language. Merapi is one of some 500 volcanoes in Indonesia, of which at least 129 are considered active. It lies in one of Indonesia’s most densely populated regions, and is only a few kilometres from the sultanate of Yogyakarta. Despite frequently giving out smoke, the mountain still attracts hikers and climbers. It takes 5 hours to climb up and 3 hours to return.
From Yogyakarta, go further North to Kaliurang hill resort by public
transport or by car.
Kaliurang stands at 900 m on the slopes of Merapi.
Quoted from : http://www.indonesia.travel/en/destination/339/merapi