There is evidence of major flooding in many areas, but not of a single flood which covered the entire earth. The release of hugh Ice Age melt lakes like Agazziz (sp?) and Missoula, and undoubtedly some in Europe and the Himilayas, would have really messed up some costal areas, which is where most of the “civilization” would have been.
Regarding Crete, my guess is that a signficant tsunami would have wiped out the port facilites, homes, ships and peoples where the shipbuilders and related artisans lived. The Cretan ships at sea would have survived, but with a decimated support system would have gradually rotted and declined in significance, leading to the weakness of the Cretan civilization and eventual conquest by the resurgent mainlanders.
Trouble remains that there’s no evidence for a tsunami; there’s not even evidence for any super-eruption from anything close to historic times. The pumice found in an Egyptian context was saddled on for years as evidence of a super-eruption; when the pumice was at last chemically analyzed to prove the link, it was found to be NOT from Thera, nor from anything close to the historical era reflected by the strata. So, *that* failure was dismissed as not important — despite the fact that it was the only supposedly solid evidence that any such super-eruption ever took place.