There's a rational wiki article which covers some of the historical, geological and more general scientific objections to the idea that Noah had a global flood: http://rationalwiki.org/wiki/Global_flood
Of course, the entire problem with taking this approach is that believers suspend all their rational thinking powers and make problems go away with 'God magic'.
'The air pressure on earth being under so much water in the sky would be the same as living at the bottom of the deepest part of the ocean - how did Noah live like that?'
'God did it so your factually based objection is irrelevant'.