Do not think too much when you see the road.
It is like a "roller coaster" but probably one of the safest roads in Bali as everyone is especially careful.

The road leads down to the lake Batur, transversing the hardened lava to the hot springs of Toya Bungkah, where there is a public bathing area you can feel the "natural sauna".

Volcanic mineral springs seep into the lake and a dip in the public bathing area is believed to cure sickness.
This is the base camp area for people who want to climb Mount Batur and has a hot spring presumed to have therapeutic traits, Toya Bungkah is one of the most interesting site around Batur crater area.

From Toya Bungkah, boats cross the lake to Bali Aga village called Trunyan. This place is notorious for its mortuary traditions. Instead of cremating the dead, as Balinese do throughout most of the island, the Trunyan community leaves the bodies to decompose naturally in a special cemetery.