@Zack To be quite fair, I ignored that the force field would have any effect on a human trying to exit the "dome". In the original idea anyone could simply walk forward and get submerged in water (no physical barrier between this air pocket and the ocean in front of the person). But further comments made by Cort Ammon, if I'm not mistaken, changed my mind about it. He convinced me that the water would be as solid as concrete, ironically creating the dome I wanted so bad not to exist.

@Zack However, the point of my question wasn't someone trying to exit the dome. I can work around that in case I commit to the concrete wall hyphotesis. But I still needed to know what happens if a person is subjected to a ludicrous amount of water pressure, because I need a scene where an observer inside the dome sees what happens if he tries to escape by swimming upwards (kind of like a warning).