Thanks again!
Frank, yes, a Gorilla pod would have been ideal but I could not have entered the site with it as photo was actually prohibited... They want to sell their own very good ones btw and taken with a tripod of course, at quite high price actually. They also want to avoid the experience to be ruined by flashes going off and this is understandable. However my camera is not equiped with a flash so there is no risk! And I did some research before entering the site, it is illegal in Slovenia to prohibit photography in a publicly run site, so I felt it was appropriate to snap a few pictures, standing with a small group of well equipped people behind the crowd. The guide was perfectly aware ot this and did not insist on fighting a lost battle...
Some of their commercial pictures were actually taken from the stairs that can be seen on the left wall. These stairs also help getting an idea of how gigantic the cave is.