So, I can't complain because I practically stole this car from its former owner, BUT I don't think he did anything other than change the oil during the 5 or so years he owned it -- certainly not judging by the condition of the leather. And also by what I just found in the trunk: About 1-2 inches of standing water around the spare and -- yes -- the battery. And it's not a recent development (which is good, in a way: I know that if I nip it in the bud then it shouldn't cause any new problems) -- there's LOTS of accumulated rust and corrosion on the spare's rim, and the entire well is stained with rust. On the other hand, it didn't rust through, so it may not have been THAT long. First question: could it be as simple as the trunk seal? There's definitely damage to it at the lowest point. Also: the water hardly drains (I had to leave it overnight after finding it), so presumably it's not coming in from below. My only worry is that it's coming in somewhere behind the battery (i.e., the right rear wheel well) -- due to a lack of a 13mm wrench and a good deal of corrosion I couldn't remove the terminal connections and thus couldn't get a good look behind it. Second question: anyone else heard of or personally experience anything like this? I'm still amazed that it didn't cause any electrical problems; it rotted away the cloth wrap on some light wiring, but that seems to have been the extent of the damage. Oh -- obviously, I've removed the water, swabbed as many surfaces as I could and sprayed the whole compartment down with WD-40 as a stopgap. I'm thinking naval jelly or something like it next, unless anyone has a better idea. Thanks for your help!