It actually had to be HIGHER than 13,000 feet since other mountains are much taller. If you integrate the volume from today’s sea level to 29,000 feet (Mt. Everest) you find the water would be about an order of magnitude MORE than all the water on the Earth today (in ice, liquid, or vapor form). A lot of water must have gone somewhere...
As I’ve written before here, there is perhaps 5 times more water within the earth’s mantle than in all the oceans on the surface. That is PLENTY of water to flood the highest mountain, should it for some reason erupt to the surface for a season.
It actually had to be HIGHER than 13,000 feet since other mountains are much taller. If you integrate the volume from today’s sea level to 29,000 feet (Mt. Everest) you find the water would be about an order of magnitude MORE than all the water on the Earth today (in ice, liquid, or vapor form). A lot of water must have gone somewhere...
You'll find good answers in the following websites about that. It has to do with the geology and make-up of the earth before the world-wide flood and the dramatic changes that happens during the time it came about, and the vast and tectonic changes that happened immediately afterwards...
It was catastrophism to the "nth degree" -- if you will ...