Reaching crush depth wouldn’t be a slow crushing. Once the first deformations appear in the pressure hull, the whole thing caves very very fast, likely over the course of a couple seconds at most, depending on the pressure when it finally gives (44psi per hundred feet, at 1800 ft would yield almost 800psi, that’s a lot of pressure, and a massive release of energy once the hull finally gives.).
The strength of the hull comes from its shape more than material strength (though that does play a massive factor).
What feels slow, and would feel like an eternity, would be everything that leads up to crush depth.
Well before you reached crush depth, you’d know you were doomed. You’d be able fight the ship for a while, trying to restore hydraulics for control surfaces, high pressure air to blow out the ballast tanks, fighting to manually close ballast tank vents if they’ve been pushed out of position, trying to restore propulsion any way you can, fighting the fire that may have destroyed your battery and filled your world with chlorine gas and smoke. All this activity and rush feels fast, it may be 15 minutes, it may be 2 hours, but all it does is give you hope. Then when you’re exhausted and everybody is looking around in a moment of calm, the last battle lanterns will fail and you’ll spend the rest of your life in a darkness you can’t possibly have imagined until that moment. You hear a lot of creaking and groaning, growing louder and more insistent over the course of a few minutes.
Suddenly, you feel, more than hear, a terrible rending of metal, and your 14 psi world becomes damn near 800 in barely a few seconds, and you never hear anything again.
I’m a submariner, I think about this every day.