The Bible does not lie
If God says he covered the whole earth....he covered the whole earth
Mt Everest included
The thought is that the water pushed the ground up which would account for the mountains.
People who have a wet basement know how powerful water is. You can seal it but water pressure will crack it again.
The Flood is a piece of mythology, pure and simple.
There are several ways this can be proven.
First, there is not enough water on the planet (in vapor, ice pack and all underground sources) to cover the surface.
Second, the flood would have happened around 2348 BC. The Great Pyramid of Cheops was built about 230 years before that. And it shows no sign of being submerged for a year. The Egyptians have a continuous recorded history from before the time of the flood to well after, with no significant breaks and no mention of the flood.