If by "no breach" you mean no flooding, that only means more water is not pouring into the boat. You might have taken in too much water already, in which case boat will keep sinking until water is pumped out (which might take a while especially if your pumps are damaged too). In shallow water, you might have chance to wait it out on the bottom, but otherwise you're pretty much done for.
Historically, if so much water got in that only way to keep the boat from sinking was blowing ballast tanks, the U-Boat commander would blow the tanks completely and tell the crew to abandon ship as soon as they break the surface.
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