I find this fascinating! Googling a bit, it seems there is a documentary on the Movile cave: <a href="http:&#x2F;&#x2F;www.dailymotion.com&#x2F;video&#x2F;x1qpffb_the-secret-underworld-movile-sulphur-cave-life-romania-national-geographic-adventures_tech" rel="nofollow">http:&#x2F;&#x2F;www.dailymotion.com&#x2F;video&#x2F;x1qpffb_the-secret-underwor...</a>