Cleithrophobia might be the most frightening (and common) phobia you've never heard of. It's the fear of being trapped, and is often confused with claustrophobia. If you're wary of elevators, or worried about doors that lock from the outside, or simply concerned about not being able to find an exit, you may have Cleithrophobia. Who doesn't have this fear? Those who venture deep into unexplored caves, where light is scarce and it's entirely too easy to get turned around and lose your way.
Like photos of other phobias, these historical photos of caves, and those who traverse and work in them, may just induce this fear; and if you already suspect you have it, now's the time to look away.