So, this wasn't really made to be anything in particular. I just wanted to experiment with some techniques, namely:

1) Generating fairly organic seeming tunnels using rendered clouds + hard mix grey;

2) Taking a stab at moderately realistic transparent water with displacement maps;

and 3) Lighting.

Here's the result, with and without grid.

Click image for larger version.  Name: experimental-cave-with-grid.jpg  Views: 135  Size: 1.70 MB  ID: 61073

Click image for larger version.  Name: experimental-cave.jpg  Views: 121  Size: 1.64 MB  ID: 61072

Scale is 100px = 5 feet.

Mushrooms by Neyjour; I changed 'em purple.

Campfire by Bogie.

Everything else consists of textures from cgtextures.com.

I'm pleased with the organic feel of the cavern shapes, but I may have gone awfully heavy-handed with the bevel-and-contour layer style.

The water ... is okay. It really needs a larger area for this technique to work best, I think. Making good water is freakishly hard.

The lighting turned out okay. I'm using two techniques here. The cave was darkened with a layer of translucent solid black. For the area of pure light around the campfire I just masked off the darkness. The glowing mushrooms and the area of pale orange immediately surrounding the campfire are Curves adjustment layers in which I've masked it to just the areas that need to glow, and then adjusted the three RGB channels individually to get the desired hue.

As I said, this is mostly playing around. It turned out okay though. Maybe somebody will find a use for it. Can't hurt to have another generic cave, right?