Titanic
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In a matter of 10 seconds, the iceberg ruptured the first five compartments including the forward most boiler room, number 6, and a small section of boiler room 5.  She could stay afloat with any two consecutive compartments flooded, or the first four smaller ones.  Contrary to popular beleif, the iceberg did not tear a 300 foot gash along the side of the ship, but instead popped rivits and caused small ruptures in the hull plating, some no bigger then that of a little finger.  In the end, only 12 square feet, or the size of a normal refridgerator, was opened to the sea.  Seeing however that the ruptures were for the most 20 feet below the water line meant water flooded into them at a massive rate, nearly 20 gallons a second through each opening.