A couple weeks ago I went by myself for a hike through an old lava tunnel cave. I needed a flashlight because it was pitch black. I found a small nook in the wall about a mile in that I could wedge myself in to. I sat down, turned off my light, and let myself feel the enveloping darkness for a long time. I cried. The only sounds were of small droplets of cold water hitting the floor and my body. I let myself settle in to the sensation of being buried alone under the rock where liquid fire once reigned. I felt at peace. When I finally emerged from the cold tunnel a thrill ran through me as warm air gushed over my skin and the distant sun found me once again. I sat and fed the birds that visited me in the remote wilderness while I listened to the gentle whirl of wind in the trees.
Depends on the complexity of the cave. If it's an acyclic graph and you only went upstream you will probably hurt your shins a lot but you will eventually make it to the exit. If it's not and you are far way from an exit without any information gradient, e.g. light or sound, then hopefully you did inform others of your solo trip in the cave.