The problem is that the pressure experienced under water actually comes from gravity (acceleration). If you accelerate at 10G the pressure versus depth under water goes up 10x (relative to Earth). So being a meter under water is the same as being 10 m under water on Earth. At 100G, it goes up to 100m equivalent on Earth, which would squish you. Also, if you were upright, head just below the surface, your feet would be at 250 meters deep equivalent and your head at 2 meters equivalent, so it would squish all your feet and legs into your middle/head. It would not only kill you, but would be really awful to look at...