Boybuloq Cave
The cave is the deepest known cave in Asia having been explored to a depth of from the entrance. At the lowest discovered level a water-filled siphon blocks further exploration. It is thought that the cave has the potential to be the deepest known cave in the world, with a theorised depth of making it deeper than the Veryovkina Cave. The explored length of the cave is .
Picos de Europa
The Picos de Europa contain many of world's deepest caves, including Torca del Cerro (−1589 m), Sima de la Cornisa (−1507 m), Torca los Rebecos (−1255 m) and Pozo del Madejuno (−1252 m). Discovery of new caves and their exploration still continues.