Unnerved by the paintings, you think about turning around and exiting, but as you turn, your flashlight plays over the walls and reveals what appears to be a void behind an oddly-shaped rock, almost hidden from view. This opening has no paintings, and you wonder if maybe it is a service tunnel or something the park employees use. You're still curious about the cave, but you want to get a better idea of what it is all about before entering one of the paths with the weird pictures, so if you can find a caretaker or someone, it would be great. Plus, the tunnel does not appear to have any "Do Not Enter" or "Staff Only" signs, so you probably won't get in trouble.
You are happy with your decision, so you don't notice the strange red-orange scrawls on the other side of the large stone. In fact, if you'd looked closer, you might have noticed a slight trench in the ground, as though the rock had originally covered the entrance to the tunnel completely, and someone (or something) had moved it aside.
Ducking your head slightly, you enter the tunnel. At first, you simply notice how black the rock making up the tunnel walls is. Almost like a lava tube, or some volcanic rock. After you have walked a ways, you begin to realize that the tunnel has been sloping downward, and the gradient is still increasing. You hesitate a moment and think about turning back, but the uphill climb is going to be much harder than going downhill, and the tunnel must come out somewhere, right?
As you continue on, you begin to sweat a bit. Thinking it is from the effort, you wipe your forehead and continue. However, you begin to realize the heat is getting more oppressive. No way, this couldn't be a real lava tube, could it? But you don't live anywhere near any volcanic activity. It felt like you were walking down into the depths of h---
Before you can finish your thought, you come to a leveling out and sharp curve in the tunnel, beyond which emanates a dull red glow and a definite odor of sulfur. In curious disbelief, you round the curve to see before you...