As a caldera formed by the eruption of a supervolcano, Lake Toba is surrounded by interesting geological formations. One of these is Sipiso-piso waterfall, which translates literally as “like a knife.” An underground river that runs along the Karo Plateau comes to a sudden 390-foot plunge before joining the waters of the lake. Water pours out of an opening in the cliff as if it had just broken through it.

Sipiso-piso is located in the hills, at an altitude of about 2,600 feet above sea level. The land surrounding the falls is filled with pine forests. In Sumatra, vegetation tends to be lush, but a massive waterfall is a never-ending source of mist, and the resulting emerald-green of the nearby flora is simply spectacular.

A well-trodden but badly maintained trail leads from the main viewpoint down to the base of the waterfall.  It requires medium physical fitness to descend and, above all, ascend back to the viewpoint.