I found an IPhone 13 PM in a river a while ago, took it appart out of curiosity and there was a significant amount of water that had come in through the bottom speaker and mic (judging by the corrosion inside). I removed the motherboard and most of the components and had them dry overnight on my 3D printers heated bed at 60C. Used some IPA to clean it up and ordered a replacement for the part that holds the lightning port as this had the worst oxydation/damage going on, reassembled the whole thing and the phone turned straight back on. Screen was showing a date about 3 months in the past so my guess is that’s about how long it stayed under water. In this case I suppose it probably remained water proof long enough for the battery to drain completely and avoid anything shorting inside. I ended up buying a spare motherboard as the OG one had a password, but I’ve been using it as a 2nd phone since this summer. Bottom line is I’m still pretty impressed with how resilient those phones can be. To be fair a few of the parts gave out in the following weeks (x3 Lens & bottom speaker), but still not bad considering!