Where is all that water [from the Flood] now?
The oceans cover over two-thirds of the earth’s surface to a great depth. The average depth of the major oceans, beyond the continental shelves, is about 12,000 feet, while some trenches are significantly deeper than Mt. Everest is high. That’s a great deal of water. So much water that if you lowered the height of today’s mountains and raised the ocean valleys, there would be more than enough water to cover the whole surface of the earth.
This raises the question: was the world different before the Flood?
Most creation researchers believe the world before the Flood was radically different from today’s world. This pre-Flood world had shallower seas (no deep ocean trenches) and lower mountains, scattered across a single continent (Genesis 1:9 implies there was just one continent). Most of today’s mountain ranges were probably built by tectonic forces initiated during the Flood. We know this because mountain ranges are full of fossils (mostly marine), and fossils are largely a Flood phenomenon.
Psalm 104:8, speaking poetically of the time of the Flood, describes the mountains rising and the valleys sinking and Genesis 8:3 tells us that the waters “receded from the earth continually.” Therefore the water did not need to rise over 29,000 ft. to cover today’s Mt. Everest because the Himalayan mountains didn’t exist before the Flood but, rather, formed during, or shortly after, the Flood by tectonic forces. (The Himalayan mountains are still growing very slowly in elevation due to the subduction of the Indian tectonic plate under the Eurasian Plate). Evolutionists also believe the mountains were formed by tectonic forces, but they believe it happened over millions of years rather than catastrophically during the yearlong Flood.
It’s likely that all of the water we have on earth today wasn’t above the crust before the Flood. Subterranean waters, from under the earth’s crust, probably supplied some of the floodwaters. Genesis 7:11 tells us the fountains of the great deep burst forth, implying there was water under the crust that gushed forth when the Flood began. Research has shown there is likely still more water under the crust than above it, even today. This is not surprising considering the earth was formed in water (Genesis 1:2; 2 Peter 3:5).