In September 1992, a large group of cavers entered J-4 Cave in Centre County, Pennsylvania. It included eight or so new cavers and several guides, and was a newcomers, orientation trip by the Nittany Grotto, NSS.
At an intersection in the basement level, one of the guides pointed to a hole that would lead to a big room and suggested some of the novices have a look. Steve Yochum, apparently a rather thin person, and a companion decided to try it and Yochum crawled in. The guide advised him to drop down into a hole in the midst of the crawl and this would take him to the big room. Yochum missed this hole, crawled on, and squeezed unsuspectingly down a crevice into a narrow chamber. As he squeezed through he remembered thinking that he was glad he wouldn't have to go out that way (there are apparently other ways out of the big room). On a mud covered floor he looked around -- there was no big room and no other way out!
After a brief episode of claustrophobic panic he yelled, telling the companion following him not to come in. The room was very small, about four by eight feet, with walls sloping up to the entrance crevice in the ceiling. The room was not tall but there was only one handhold near the crevice and no footholds. Yochum managed to lift himself with this hold and got his chest to the narrowest point but it seemed that his body would no longer fit. He dropped back down.
Another of the guides approached as far he could squeeze in the crawlway above and they discussed the situation. Without excavation no one else could get close enough to help. Yochum tried the climb again and again failed. He realized that when entering, he was relaxed -- when he tried to ascend, his muscles were taut and took up more space. He passed his helmet and sweater out, tried again and failed. He took off his jeans and t-shirt -- he still couldn't make it. He slumped tiredly to the floor. He swore to himself that if he got out he would never enter a cave again. After resting he tried again, to no avail.
As he rested he suddenly had an idea -- if he were to go feet first he might get his feet and legs up through the hole, and be able to push his chest to the narrowest part with his arms. His feet would then be within reach of the caver in the crawlway. If this caver could pull him out, he would be relaxed effectively thinner. As Yochum says, "It worked!" He decided not to give up caving.
NSS News, December 1994 (Part 2) V52N12, Page 381.
Steve Yochum "Cave Stories" Nittany Grotto News July 1994, p 56.
Situations like this may seem like nothing once they are resolved but there is a great potential for a huge increase in seriousness of the problem. The successful outcome here may be due to the suppression of panic by the victim. He kept at the problem and found a solution.