Did Noah's flood really occur? PLEASE, SCIENTIFIC ANSWERS ONLY!!!?

I was taught as a little kid in sunday school that there was a great flood that nearly wiped the human race except for noah and family. But now, i'm hearing geologists say it never happened. did it happen or not? what are the evidence that it happened or not? and if it didn't happen, why do so many cultures have stories about it. i mean the bible's account and the babylonian account from "the epic gilgamesh" is so strickingly similar, u Know - some deity tells a little man to build a boat, stuff his family in there with some animals and sail away as the they wipe the earth clean with a flood because of man's wickedness.