Like a rotten Apple.
Looks good on the out side but, on the inside,
what color roses do you want.
Especially if it is full of water.
After you drain it then walk in. Usually not far from the entrance it was common practice to have a
winze, A shaft any thing up to a few hundred feet deep straight down. Still full of water and covered over with rotten timber.
Then there is the pressure created after you have drained it by the surrounding water table.
Hope you can Ski. LOL
Then finally contend with Gas.
.
Sorry to be a prick but looking at your
first post you do not know the inherent dangers of
an old mine.
Tread carefully my friend as I would like to meet you one day.