I have to pay 5 euros to some guy, who will the open the gates for me and allow me access to the underground
Nothing like a good bribe to get you in, that wouldn't work here so well.
You are more adventurous than me, solo down in a mine.. I wouldn't have done it.
I´d like to think of it as a bribe, but in reality it was just fuel money - the tunnels were on private property, I called some guy who drove there, opened the gates and drove back again to close them later. And it was actually quite innocent, the tunnels themselves :D
Here they are too adamant about safety and that's why UX is gaining so much popularity. There is no safety and it's up to you to keep yourself safe.