> You can't go infinitely deep anyway, because eventually the pressure will penetrate the seals.
This is actually the least useful reason why you can't go infinitely deep. For exploration you will basically always want to be near the bottom of the body of water because mid column is just extremely boring, so you will want to make sure that your pressure tolerance allows for that. We just haven't found any infinitely deep bodies of water yet.
You can't go infinitely deep anyway, because eventually the pressure will penetrate the seals.