I have been hiking/mountaineering for quite a few years now. But, I have never been into a deep cave as yet. We are planning to explore a natural cave that we'll have to rappel into. The cave is unexplored for nearly a 3 decades now, and evidently has a way out. We plan to explore and search for the way out on the other side, if not then we intend to jumar back up to the top.
The source of information about the presence of potable water and the exit on the other end is genuine.
Edit : Its a natural cave. To get into the mouth of it, one needs to rappel down a rough 200 ft. Its rich with Flora and Fauna, an ideal habitat for reptiles and Bats, a mild stream of water that goes through it, but one never gets into a depth more than 4 ft. In the month of March, usually it doesn't rain here in India, so pretty safe with water flow which one needs to deal with for a very short distance in order to cross it.
Apart from carrying flash-lights/torches, Medical kits, safety, what are the precautions that one should take during such an exploration?