The Snezhnaya-Mezhennogo-Illyuziya cave system in the western Caucasus

The Snezhnaya-Mezhennogo-Illyuziya (SMI) cave system in the Western Caucasus is one of the largest and most complex karstic systems, with a known depth of 1,760 meters, an extent of over 32 kilometers, and a volume exceeding 2.7 million cubic meters. This branched, arborescent network features sub-vertical shafts connected to underground rivers, including Snezhnaya (1,970 m a.s.l.), Mezhennogo (2,015 m a.s.l.), and Illyuziya (2,389 m a.s.l.). The system's largest chamber, the Thronnyj, measures 309x109x40 meters. Research since 1971 has revealed an average underground river discharge of approximately 500 liters per second and temperatures ranging from 0 to 6.5°C. Ongoing studies continue to explore this significant geological formation.

Mavlyudov, B. R. (2016). The Snezhnaya-Mezhennogo-Illyuziya cave system in the western Caucasus. Boletín Geológico Y Minero, 127(1), 219–235. https://doi.org/10.21701/bolgeomin.127.1.015