Originally Posted By: sodak
In the Midwest, dry underground cisterns kill people every few years or so. I think that the CO2 (or some other gas) collects in them, and people climb down into them and pass out and asphyxiate. Just keep that in mind if ever going into one.

That is almost the start of a thread about confined spaces and confined space entry. It might be a good thread to start if it does not already exist.
May set off to explore without any sense of direction or how to return.