[97 Stang]

I've got a leaking problem and I have no idea where it's coming from. The water pools up on the rubber mat that's under the driver floor mat. It's more than just condesation, it's an actual little puddle of water. The carpet around it isn't wet, it's only on the rubber mat. I can't see where it's coming from if I lay down and look, so just wanting to know if anybody else has had this problem or knows what could be letting the leak in.