Aya Lake, Natural lake in Altai Krai, Russia

Aya Lake is a freshwater body in southern Siberia's Altai region. It features clear water and a varied shoreline framed by forests and meadows.

The basin of Aya Lake formed after the last glaciation, when glacial outburst floods from the Katun and Chuya valleys carved it as an evorsion cauldron between roughly 15,000 and 7,000 years ago. The lake is part of the Altai scabland. In October 2003 the Altai Krai administration created the Aya Nature Park to protect its surroundings.

The name Aya comes from the Altai word for moon. An Altai legend says the moon descended into the valley and seized the cannibal Delbegen to save humankind; the depression left where it touched the ground filled with water and became the lake. A small island with a gazebo stands in the middle of the water.

The shoreline is reachable via regional roads with multiple access points depending on the season. Warm months provide good conditions for swimming, fishing, and boating.

The lake has no surface outlet; it is fed by underground springs that rise from the bottom, and its water level fluctuates slightly. In November the lake freezes, and cleared stretches of ice are used for skating.