Indonesia has the best sites when speaking about it’s collection of volcanos. A stop in Kaban Jahe and Berastagi in North Sumatra about 2 hours from Medan had brought me to one of this volcano.
We had the opportunity to climb Mount Sibayak and observed the sleeping volcano. The last eruption was a century ago. Geothermal activity in the form of steam vents and hot springs can be found. Th steam vents producing crystalline sulphur. These sulphurs are still being collected by locals as part of their daily income.
Kaban Jahe and Berastagi are situated on a high. It can be a little chilly during the day but the hot spring kept us warm.
Another fun site to go is the Sipiso-piso waterfall. I didn’t go down but Kamal had a dip in in the cold water. Worth going. The scenary was magnificient.