Hell, even a spacecraft hull differential is typically the same as one atmosphere, total. By about 10m down you're already 1 atm of additional force beyond the 1 atm that exists just by existing at sea level. So, at the depth of the Titanic (around 3800 meters) you're at around 380 atm of pressure, give or take.
And pressure differences for submersible hull are orders of magnitude greater than pressure differences for aircraft hull.
Hell, even a spacecraft hull differential is typically the same as one atmosphere, total. By about 10m down you're already 1 atm of additional force beyond the 1 atm that exists just by existing at sea level. So, at the depth of the Titanic (around 3800 meters) you're at around 380 atm of pressure, give or take.