Tangkahan is the much quieter sister destination to Bukit Lawang, about 40 km north along the edge of the park where the Buluh and Batang rivers meet at the boundary of the protected forest. The setting is striking: a wide jungle valley with hot springs, jungle pools, and the rivers themselves available for swimming, tubing and short rafting. It is an easy place to slow down for a few days after the more intense scene at Bukit Lawang.
The other reason people come is the Conservation Response Unit, a small herd of working elephants that patrol the park boundaries to discourage poaching and illegal logging. The elephants are former captive animals from elsewhere in Sumatra, retrained for forest work, and visitors can join the morning bath in the river — much more interesting than the elephant-back tourist riding that has thankfully been phased out. The CRU does not offer rides; the experience is bathing and feeding only, which is exactly the right way to do it.