darth_ender said:

Well then, I'd only speak for myself, not for Catholics (which I am not), nor even Christians in general. I believe that if the flood did take place, it was probably a local phenomenon. But that's just me.

That is also my stance. The word used in the book of Genesis can mean both "world" or "land," the latter implying that it extended from horizon to horizon and only looked like it covered the entire world from Noah's POV.

At Ur, there is a layer of flood deposit which shows that the city has been destroyed by flood at one time. Abraham came from Ur, so he may have brought the story of that flood with him when he left. Another theory is that since the Black Sea was once isolated, the flood may have been an event (probably caused by a big storm which flooded the area in a few days) which joined it to the Mediterranean. Towns have been discovered on the floor of the Black Sea, backing up this theory.

I do however believe it was a historical event of some kind, because the story is so widespread and so many similarities exist between the stories.