An easy walk thru rainforest takes you to the start of the volcanic area. Takes about 1.5 hours at a slow pace. Another 30 minutes gets you to steam vents with sulphur condensed over the rocks and a noise like a jet engine. Then walk past the main crater which people have 'decorated' using large rocks to write their names. You can walk up above the crater for views over berastagi including the geothermal plant and hot springs. Its an hours walk back down. Get your driver to meet you and drive to the hot springs - or its a 45 minute walk. Have a soak in the mineral water while you enjoy a bintang. Change facilities are not great, so take a sarong or large towel. Our guide, Juan, was great. Not really necessary, but there are a few places where the track could be hard to find.