My wife and I like to explore caves (and one mine, so far), but as part of a nice, touristy, well-lighted, gentle slopes and stairs (or boats!) experience.
When I was on submarines in the Navy we had a dry dock period for refit, and as the engineering duty officer I had the delightful task of “diving” large storage tanks after they were worked on, prior to “closing them out” and calling them ready to go back to sea. Basically I just looked for loose tools, something that should have been tightened that wasn’t, and so on. (We had a sharp crew, I never found anything.) So I was crawling around one tank on my belly, very tight, where just rolling over took about five minutes, and forget about turning around. I had an electric light with the cord running through the hatch, plus a backup flashlight. So I’m basically done, but at the far end of the tank, when my petty officer who is my “topside” contact, MM1 MacArthur, decides to play a prank on the lieutenant junior grade. So he hollers down into the tank, “I’m gonna take a smoke break, Mr. H., be back soon!” And unplugs the light, throws in the cord, and shuts the hatch. And dogs (locks) it. So I’m there in darkness. Really dark darkness, too. So I spend the first five minutes wiggling around so I can get to my flashlight that I had buried in my pocket; having determined that yes, the light still worked and yes, still very dark, I turned it off to save the battery. (No, I don’t know for what.) I took another five minutes to get into a position that was only somewhat uncomfortable and took a nap.
At some point the hatch is opened, Petty Officer MacArthur plugs my electric light back in, and hollers, “You doin’ okay, Lieutenant?” “Just fine, Mac,” I holler back, “took a nap, didn’t have much else to do.” “You ready to come on out?” “Sure, Mac.” And I commence to wiggle my way backward and out.
BUT! Unlike your situation, Annie, I knew people would be coming for me, and that they could get to me. If I’d been trapped as you were, it would have been much, much harder to kep my cool. You are a tough person!