Allot of the survivors of the Bismarck claim they sunk her themselves with explosives, and AFAIK this has been confirmed by underwater investigations. However lets face it, she was done for, and although it might have been the explosives which sank her, she was already put permanently out of action by the British warships long before that decision was ever made.
And about the hull of the Bismarck, although I'm not 100% sure about this, I seem to remember that the upper bow hull had been completely penetrated by a British 15" shell which even went out the other side without exploding. - The British throughout WW2 had problems with fuzes which later caused them to abandon the use of them completely in armor piercing rounds. The Germans on the other hand had great succes with fuzes in AP shells (As the HMS Hood testifies), and therefore stuck with it in their AP designs, improving them over the years.
