There is positive evidence that there was no worldwide flood.
be *absolutely certain* to specify that the worldwide flood of which there is no evidence is the mythic one which is said to have drowned even the tallest mountains to a depth of yay-or-so meters...
don't let 'em 'scape crawdadwise, by trying to make out the worldwide drowning of coastlines at the close of the last Ice Age as the literal equal of the mythic deluge.