I can't say one way or the other. There is enough water to cover most of the earths surface if it's not tied up in ice at the poles so it's physically possible. And there is also evidence of water coverage over many parts of the earth that are not near any ocean. However the story could also be interpreted in terms of a localized flood covering all of the known earth.

I do believe Noah was a literal person and I do believe there was a flood. I even like the idea of a global flood as it seems to allow one to explain some phenomena observed in Geological formations. However I'm not a Geologist so my opinions there are pretty uninformed and could just as likely be wrong.

Its true that a lot of land would be covered by melted ice but even then, over 90% of earth would still be above sea level as shown here: http://www.dailymail.co.uk/sciencetech/article-2488452/Map-r...

Also, fossil evidence doesn't not support a worldwide flood. If a worldwide flood would have happened you have have fossils from that era all over the place in sediments of rock, but you don't. They are all found neatly organized in their own respective layers. Here is some more info if you are interested: http://rationalwiki.org/wiki/Global_flood#Fossil_layers

I think a localized flood is a much better explanation for people who believe that part of the bible.