A 1 (one) meter high tank that has a hole with threads for a screw to fit tightly, is immersed to. say 50 (fifty) meters in water where the pressure is about 5 (five) atm. The precition is so good that the screw fits so well as if there is no hole at all when the screw is driven in (closes) the hole. What pressures are there in the tank when the hole is closed and open.