Just read this on another forum. I'll refrain from comment as my early exploration into underground places included use of an inflatable dinghy with little regard for the consequences in the event of failure. Ah, the follies of youth!

http://www.28dayslater.co.uk/forums/showthread.php?t=7445

and

http://www.28dayslater.co.uk/forums/showthread.php?t=7559

Actually, Peter, quite an amusing write up, nice the bit about restoring faith in human nature.