Hello, me and Some friends of mine have the idea to explore the underground catacombs of paris, and not, The tourist way of course, we are searching for a detailed map, or maybe Some cataphiles to acompany us or giving us tips or any kind of information

If you mean just wander around down there by yourself I'm not sure this is possible. I know there are large sections closed off because they are potentially unsafe - although many were used by the Resistance in WWII (obviously the Germans presented a greater risk).

If interested I would check out what tours there are.

But then I don't want to be trapped underground with no one knowing where I am.

It is a very interesting tour. The Paris catacombs are former underground limestone mines that were turned into ossuaries as old cemeteries inside the city deteriorated. As far as I know, for the one I visited at Denfert-Rochereau, there is one way in and one way out, and you wend your way through it on a self-guided tour like everyone else. Visitors and their personal effects are inspected as they leave, in case anyone is thinking of grabbing some "souvenirs."

You have to be in touch with <i>cataphiles</i> for a certain amount of time to ever be invited on the visits inside Paris, because by then you would have to have full equipment (boots, ropes, headlamps...) and of course be prepared to pay very high fines that are applied on anybody caught by the police (who regularly patrol the favorite areas). Beginners usually start by visiting the underground quarries of Bougival, the most spectacular one being the "carrière aux lions" which has huge arched ceilings the size of a cathedral. However, the last I heard, it had been completely sealed off again. It takes a while for the cataphiles to break through the door or the find an alternate access.

I was young and foolish back when I used to engage in that activity, and I absolutely do not recommend it.

kerouac, this subject obviously goes much deeper than I imagined.

Anyway, the <i>cataphiles</i> never illegally visit the "official" catacombs which have no interest for them since anybody can go there during the day.

Thanks for the replies so far, are the quaries Also illegal? And i want to take the risk to get a fine, i just want to go into the catacombs, Anyone got Some tips, unless the tip is to not go down there

Here is a pretty good overview of subterranean Paris with recommendations, and also some other links at the end:
http://keblo1515.free.fr/souterrinterdit/catacombes.htm

The Paris Catacombs are the only legal visit to the subterranean tunnels. All other entrances are not legal and there is a police force who work the tunnels and close up entrances as they find them.