Batur remains active so check the current situation for climbing at wwww.vsi.esdm.go.id – it’s mostly in Indonesian but it is clear if a mountain is on alert. Climbing Batur is best in the dry season (April–Oct).
There’s a choice of routes up Gunung Batur. If you have your own wheels, the easiest route is to drive to Serongga, off the Yehmampeh road, west of Songan. From the car park, it’s thirty minutes to an hour to the highest peak and largest crater, Batur I.
The most common walking routes up to Batur I are from Toya Bungkah and Pura Jati. The path from Pura Jati is shadeless and largely across old lava fields. From Toya Bungkah, numerous paths head up through the forest (one starts just south of Arlina’s guesthouse) and up to the warung perched on the crater rim. Allow two to three hours to get to the top from either start and about half that time to get back down.
A medium-length trek involves climbing to Batur I, walking around the rim and then descending by another route.
In daylight, you don’t need a guide from Toya Bungkah or Pura Jati if you’ve a reasonable sense of direction, but you shouldn’t climb alone and you should let somebody responsible know where you are going. If you climb in the dark, which most people do to reach the top for the fabulous sunrise views, you’ll need to leave around 4am and a guide is vital.