Skocjan Caves

I went to Skocjan last summer. I was dealing with the after-effects of a badly sprained ankle and not feeling completely stable. Still, I don't remember anything particularly scary. There are railings in the obvious places (possibly even everywhere, but I don't remember). There probably were a few places where the walkway crossed an open area (pit), however. I imagine the walkway was damp, but again it wasn't an issue for me; I was wearing lace-up walking shoes. What I do remember is that the walk from the ticket-sales area to the cave entrance (done as a group) was a bit downhill and at least partially unpaved. There were some loose leaves, which would have been wet had there been recent rain. That was the area that made me a bit nervous, because of my ankle. No one else seemed at all concerned, so I had to walk a bit faster than I would have liked to keep up with the group.

I think if you use Google you'll turn up enough photos to have a pretty good idea of the conditions. There may even be some video on YouTube.

Acraven has given you a good summary, I just want to add that you can't avoid crossing the bridge, as it's a one-way tour, entering the cave at one entrance and exiting at another. That said, most reviews of the caves by people who have a fear of heights (that I've read) stated that it wasn't too bad. The cave paths are in good condition, having been refurbished just a couple of years ago, as was the bridge, and there are handrails where necessary.

The inside temperature is around 55 degrees Fahrenheit and humidity is high, so the caves are damp. Shoes with a well-gripping sole are a must, definitely don't wear flip-flops or sandals. That is going to be your best defence against slips and injuries.