The molten material of the igneous mantle below the earth’s crust seeths below us, the thickness of the crust of the earth comparable to just the thickness of the skin on an apple, so it’s certainly not inconceivable that the mantle could swell up under the oceanic crust to raise the sea level to a catastrophic degree, flooding much of the continents.
The average depth of the oceans today is about two miles, so if the mantle swelled up under the oceanic crust (that crust like the skin on an apple) to raise the ocean floor half of that two mile average depth, then thousands of feet of sea level risen would flood onto the continents, inundating all but the high mountain ranges.
When you realize that the newly configured ocean basins sank after the runaway plate tectonics (hyper continental drift) of Noah’s Flood, because the new ocean floors were hot lava which when congealed gained density to sink down on the plastic mantle material below, while the mountain ranges were upthrusted because crustal plates were crashing into others, then you can see that biblical Noah’s Flood is certainly plausible, and in fact, proven by the geology we see when honestly analyzed.
Uniformitarian geologists of the darwinian bent say that no scientists believe Noah’s Flood as real history and scientfic fact, but what about John Baumgardner who worked for many years at Los Alamos National Laboratories? See some of his great work here http://globalflood.org, redeeming the inclinations of the early continental drift advocates Pellegrini and Wegener, the hydrology and archaeology after the Flood outlined here http://genesisveracityfoundation.com, the science of the future, old school man.