Tsivlou lake, Mountain lake in Peloponnese, Greece.

Tsivlou Lake lies on the slopes of Mount Helmos at about 700 meters elevation. It covers roughly 8.3 hectares and reaches a depth of about 80 meters. The lake formed when a landslide blocked the Krathis River, and its name comes from the village of Tsivlos, which was partially submerged.

The lake was created on 24 March 1913, when a major landslide in the area blocked the bed of the Krathis River on the slopes of Mount Helmos. The name comes from the village of Tsivlos, which was partly submerged after the landslide. Local tradition also calls it Mavrolimni, the Black Lake, for the damage it caused.

The nearby village of Zarouhla displays traditional mountain architecture with stone buildings and family-run tavernas serving regional dishes. Visitors can observe local life as residents move through the area going about their daily activities.

The lake lies near the villages of Peristera, Agia Varvara and Zarouchla, on the slopes of Mount Helmos at about 700 metres. Hiking trails run around and close to the water. The lake is within the Chelmos-Vouraikos National Park.

Local tradition calls the lake Mavrolimni, "Black Lake", because of the damage the 1913 landslide caused. The lake takes its own name from the village of Tsivlos, which was partly submerged when the Krathis was dammed.