This is very interesting and got me to thinking about, what else, RPGs!

I did some spelunking back in high school. Our band directory had an interest in geology and taught a high school class on geology for several years and took students to a couple of caves. This was in Missouri, the cave state, and we drove from the eastern suburbs of Kansas City to the caves west of St. Louis, in Meramec State Park, not to be confused with the commercial Meramec Caverns. There was one cave we couldn’t enter at that time of year due to an endangered bat species that was in hibernation the part of the year we were there. The one cave we were able to enter had a very cold stream coming out and got narrow and low very quick. We had to go sideways where we could stand and had to crawl on our stomachs in other parts.

It was a hot spring day and the water was like ice. One could easily get hypothermia even in summer.

In college and a few year after, I went on several canoe trips on some of the rivers in south-central Missouri, like the Meramec and the Current, and those can be very cool, but feel great on a hot sunny summer day!

The Current River is well named. There are places where it is only about 3 feet deep and if you lay down, or were to fall or be knocked over, you can get swept quite a bit down river, 30 to 40 feet or more, until you get your bearings and can plant your feet. Even if you keep to your feet, you can’t run without the danger of falling. This was while in sneakers and shorts. Someone in armor and weighed down with a pack would have their stance shifted to compensate and could very easily get knocked over. Just something to think about. Deeper than three feet in a swift river would be even more challenging. Where there are relatively sharp bends in the river with a limestone cliff, the river will dig down and create a deep area. Such places are good to jump off the cliff. CAUTION: I knew a guy who dove head first into one of these places headfirst and died because he came down in shallow water and broke his neck. Always make sure of the depth of the water before jumping off a cliff.

I have also taken tours of some smaller commercial caves and they have very interesting rock formations, very slick stone, made slick as ice with water.

I also recall stories a few years ago about a cave with a secret location in Mexico that has giant crystals. The pictures were cool. I will leave it to the reader to do a google search to see what I mean.

Deepest Known Cave in continental USA.

Subtle entrance to Tears of The Turtle cave [Broken Link:https://www.flickr.com/photos/elliot_stahl/7736961804/in/photostream/]. This type of entrance would be very hard to miss. This is a neat album with more than one cave and gives some ideas about how caves look.

Double Date cave Entrance [Broken Link: https://www.flickr.com/photos/elliot_stahl/7737173918/in/photostream/] – This looks like a mine to me. This could confuse characters without a mining background to think they found a mine. Dwarves or gnomes would know better.

One also has to be careful in caves. I recall the movie I saw as a kid and found it via Google. Ace in the Hole AKA The Big Carnival with Kirk Douglas, based on a true story.