You will die of hypothermia in water that’s 90 degrees. Water will make your body temp. the same as it.
I swam in the Atlantic for 4+ hours with no wet suit that was 59 degrees many years ago. I'm still here with all my toes. The body has its own heating system and insulation.
It'd eventually give you hypothermia, sure, but how long? At 90 degrees, a LONG time for some of us that are well padded.
I just assumed the sub never submerged again. Why would it need to? WWII was still YEARS off.
But the boat thing in Temple of Doom, the Crystals Skulls somehow becoming a flesh and blood alien, the "old" Knight who lived over 700 years but still looked ancient. The carrying the Grail across the seal working like "magic" when all the other traps were clearly man-made (how'd they convince "God" to booby-trap the seal to the grail?) Why did they say the grail wasn't gold yet the inside seemed to be lined with it anyway? It goes on and on. I suppose you can't enjoy the movies if you let it get to you.
The biggest one that bugged me in Raiders from when I was a kid even is why was there just sand inside the Ark? Stone tablets wouldn't turn into fine sand even over thousands of years, especially protected inside a golden wooden box. Did someone steal the contents and some sand got in there from the sandstorm that buried Tanis? Maybe the tablets were deeper under the sand for that reason and they never got a chance to look? What was with the angels? The flame, OK, from the Old Testament. Inside the Ark? God didn't actually live inside the Ark.... How did the Nazis lift the lid without dying for that matter? Touching it was a big no-no. Supposedly you could disable whatever "trap" it had with the top priest ceremony, but how would Belloq know it? I guess he clearly didn't since he died....
Ah well, the Indy movies were still great. You have to suspend disbelief sometimes I suppose. It was the character interaction that really made them work which is perhaps why Temple of Doom doesn't rate quite as high as Raiders and The Last Crusade.
The Crystal Kingdom.... I dunno. The ending ruined it for me more than anything (and I watch Ancient Aliens all the time, but that didn't come close to making sense. How did the alien come alive from several skulls and why take off, etc.? No clue. No way to know any clue. It was a downer of an ending. The endings made more sense in the other movies even if the details did not.