I apologize for being such a broken record ... But if Frontierland ever gets an expansion ... I'm so hoping on a faithful recreation of Rainbow Caverns, in either a queue, or portion of the ride. And what I mean by "faithful" ... employ the same effects as they were used. Right down to the faint "echoing" music it used. As Bob Weaver describes ... the fluorescent paints within the waters were the only real light to be seen, in the entire cavern. As the black-lighting reflected against those waters. And could barely make out the outline to anything else. Perhaps Bob can give a more specific account of what was illuminated.
On a bright day entering the cave ... I'm sure it was pretty dark. But at night .. with our eyes more adjusted ... I can almost picture a little more illumination.