Sipisopiso Waterfall, 120-meter-tall waterfall in Karo Regency, Indonesia.

Sipisopiso Waterfall is a 120-meter drop in Karo where water emerges from an underground river through a cave opening in the rock face. The water falls in a clean vertical line, cutting through the air as it descends past layered rock walls to the pool below.

This waterfall developed naturally over thousands of years through water flowing within the ancient Lake Toba caldera. The underground river carved through the Karo plateau, eventually breaking through the rock face to create the falls we see today.

The name Sipiso-piso comes from Mount Sipisopiso, the roughly 1,860-metre peak directly northeast of the falls; "piso" is the Batak word for knife, so the name is often linked to a knife-like shape. The falls lie near the fishing village of Tongging in Tanah Karo, and the nearby vantage point is used for viewing the falls and Lake Toba.

The path from the main entrance down to the foot of the falls is a staircase of 651 steps, and the climb back up is the harder part. The nearest town is Kabanjahe, about 25 km away, and the falls stand near the fishing village of Tongging. A vantage point near the entrance looks out over the falls and Lake Toba.

What makes this waterfall unusual is that water suddenly pours from the rock face without any visible surface stream feeding it from above. The underground river remains hidden, giving the illusion that the water emerges mysteriously from the stone itself.