Deno, Mountain summit in Sofia Province, Bulgaria

Deno is a summit in the eastern Rila Mountains reaching 2,790 meters. The peak features steep slopes on its northern face and gentler grass-covered terrain facing south.

The mountain formed through geological activity involving gneiss and granite-gneiss rock. These stone types created the terrain that exists there today.

The name Deno comes from the peak being the first struck by the morning sun when seen from the villages at the foot of Rila, so it was linked to the start of the day. The summit stands beside the Saragyol (Zhaltoezerniya) Cirque and its three glacial lakes.

The summit is reachable by marked hiking paths from the Borovets resort area. A nearby mountain hut at Musala offers lodging roughly 1,280 meters west of the peak.

The name Deno comes from the peak being the first in Rila to catch the morning sun when seen from the villages at the mountain's foot, so it was linked to the start of the day. The Saragyol Cirque, holding three glacial lakes, lies to the northeast, and a deep northwestern gully keeps firn snow all year.