Vjetrenica Cave in Bosnia Sets Global Record for Underground Species

The Vjetrenica Cave near Ravno in the Popovo Polje region of Bosnia and Herzegovina hosts almost 230 subterranean animal species, the highest known biodiversity for any cave worldwide. More than 90 of these are troglobionts, organisms that have fully adapted to life underground and cannot survive outside it.

Scientists have described 37 species for the first time from this cave, making it the only known location for these organisms. Unique inhabitants include a blind, eyeless salamander often called the "human fish," and the world’s only known underground tube worm. Many of the species are considered living fossils, relics of ancient geological periods.

Vjetrenica’s seven‑kilometre network of channels maintains a constant temperature of about 11 °C and contains over a hundred small underground lakes. The site has been a protected natural monument since the 1950s and was first mentioned by Pliny the Elder in 77 CE. Archaeological finds within the cave include ancient drawings, bear bones, and a leopard skeleton, underscoring its long‑standing significance.