"Deep cave explorations in the Western Caucasus: Connection of Illjuzia Cave to the Snezhnaja-Mezhennogo system sets it the World's 2nd deepest cave.
According to the report of Alexey Shelepin, the leader of the ongoing expedition of the Speleological Commission of the Russian Geographic Society (Moscow), Illjuzia Cave has been connected to the Snezhnaja-Mezhennogo System on August 2nd.
The system is located in the Bzybsky Massif adjacent to Arabika, the host massif for the world’s deepest cave Krubera (-2.158m). Illjuzia Cave is the uppermost entrance to the system at 2390 m. The amplitude of the Snezhnaja-Mezhennogo-Illjuzia System is now 1750 m and lenght is 23 km. The connection is a culmination of long-lasted efforts in Illuzia Cave. Congratulations!"
Info from: Speleogenesis