Let's talk about some specific hazards involved in exploring old mines. First let me parade my credentials: I have been doing this since about 1972. I have a degree in Geological Engineering and took every Mining Engineering course I was able to at the University of Arizona. I have been in more old mines than I can even remember or count. I have spent entire days and nights underground in large mines. Here is a list of what I consider to be the most serious dangers, and I have tried to place the most serious dangers first, just to give people something to argue about:
Most people should not explore old mines. I say this because I have not put this site together to entice people who have a casual attitude to just rush off underground. To do it casually would tell me that you shouldn't be doing it at all. However, if you are in shape, have the right equipment, and the right attitude, you can do this with a reasonable level of risk.
For some people exploring old mines is a relatively safe and reasonable occupation. For those who do care to do it, lets talk a bit about some of the specific hazards. You may also want to read this collection of close calls as well as these stories about bad air.
Precious few mines pose imminent danger of cave-in, and those that do usually advertise their tendencies by confronting you with huge piles of rubble that have already fallen down and which you must climb over and around. Think about this a minute. Most old mines have been sitting around for years and years. Mine "tunnels" were originally constructed to allow workers to come and go and move around more or less easily and safely. Over the years loose rock and areas of the mine have already fallen down. If a mine opening has stood unsupported for tens of years and today looks clean as a whistle, it was carved through solid rock and is likely to stand till the end of time. On the other hand, if the original miners used lots of expensive timber to keep the place from falling on their heads, and over time moisture and fungus has rotted that wood and today it is sagging and dripping ... well you know where to be on your toes.
Here is my first and best safety tip: Not every mine, and not every part of every mine needs to be explored! Knowing when to say, "we shouldn't be doing this" and being able to say no to yourself is an essential part of safety in any risk sport.
Never do this kind of thing with people who will make you feel the least bit bad about saying, "No, I don't think we should do this."
Also, don't think of doing this alone.
Bats are fairly often encountered underground, and frankly I enjoy seeing them. If a large colony is present, you should be concerned about the impact you may be having by disturbing them. A large colony will be evident by the accumulation of a lot of guano and a definite smell. You should be concerned about histoplasmosis (a fungus in bat guano that can cause severe infection of the human respiratory system). This is a more serious concern that the usual worry about rabid bats (not that rabies is not also a possibility). Every bat I have met is phenomenally skilled at avoiding me in flight and I have never met one that seemed the least bit interested in coming in contact with me.
The risk of being buried alive is of much less concern than the risk of being smashed flat. Most mines have places where there are large pieces of rock waiting to slide, tumble, or fall. Don't expect boulders to be stable and avoid situations where your leg could be trapped or crushed if rock piles decide to shift when you are walking across them. If you decide to crawl under a set of broken timbers supporting an unknown load of broken rock, just stop and think a minute about just what the consequences might be if your passage disturbs the arrangement.
Uncle Tom's Old Mine Info / firstname.lastname@example.org