| Tucked away in the Western Caucasus mountains where Europe meets Asia is a hidden geological wonder. Thousands of feet below the limestone surface, enormous caves stretch downward like the hollow roots of some gigantic tree. Called the Arabika Massif, this area is home to the four deepest caves in the world, including the very deepest, Veryovkina. Would-be spelunkers may have to use their imaginations, though: The mountainous terrain is less than hospitable, and the caves themselves are located in fraught political territory. All are within the borders of Abkhazia, a breakaway state recognized by much of the world as part of Georgia but with increasing ties to Russia. The location of Arabika Massif's limestone, its thickness, and its gentle slope toward the Black Sea create the perfect conditions for these huge caves, and the world record holder isn't set in stone — pun intended. It was only in 2018 that speleologists (cave scientists) discovered that Veryovkina was actually deeper, at 7,257 feet, than its rival Krubera's roughly 7,215 feet. Veryovkina may not hold onto its record forever, though, as speleologists plunge ever deeper into the world's caves in search of unknown species and the secrets of Earth's geological past. Yet based on the current rankings, it seems like a fair bet that the deepest-cave crown won't leave the mountains of Abkhazia any time soon. | 
