so you know them little window things. those are potholes if you smash them that causes a flood.
but if you can't find them noclip out then when you found one smash it. but if you look there isn't a flood. just noclip to the bottom of the sub (what you are in) and there is a flood happening
. i think the flood gets faster if you break more potholes/windows. yeah comment if you know more