At a depth of 100 metres - and high-speed submarines would probably have to go deeper - the pressure outside is ten times that prevailing inside the hull.
Kubunzulu beemitha ezilikhulu iinkwili ezinesantya esiphezulu ziyakufuneka ukuba zingene nzulu-uxinzelelo olungaphandle luphinda-phindwe kalishumi kunolukhoyo ngaphakathi kwesiqu senqanawa.