Where the heck is the water coming from? First decent rain we had, the other day, the driver's floorboard is full of water. Leaking underdash, on left about 2-3 inches out from side wall. I can see up and peel back what looks like insulation, the leak is from above that. So, where's it coming from, before I tear the dash out lookin'. What's up there TO leak? Thanks.

You may want to move this thread to the suzuki forum. 

Other than that, if it is a Samurai the cowl vent, below the windshield on the outside, gets plugged up with twigs and leaves. Once that has happened, your drains get stopped up and the water backs up and comes inside. You will need to clean the drains and your heater box. The drains look like little black hoses coming out of the firewall in the engine compartment. There are 2 of them, one on each side.

In the meantime, you could get a piece of flat magnet, like the stuff for advertising that they put on car doors, and make a cover for the cowl vent.

If it's a Tracker..... well, I don't really know.