Then where did the water come from? To answer this question I will describe the Hydroplate Theory. For a better overview see Brian Nickle’s 2:45:00 video or read Walt Brown’s online book.
This theory starts with only one assumption for the starting condition of the created earth. There was a layer of subterranean water. This layer was between the earth’s crust and the mantle. As the Bible says, He separated the water from the water below. This is supported by the fact that both times scientists have tried to drill to the mantle (kola dig, and KTB dig), they hit very salty water. This water surprised the scientists because around past 5 miles, the pressure is so great that no crack can form for water to enter. The pressure is so great on the rock that it forms a seal so the the water in the ocean cannot get into it.
Since most of the water in today’s oceans would have at first been in this underground layer, the original earth was all one connected continent. In many places around the world, the earth’s crust would have dropped down to the mantle forming pillars, while the rest of the earth’s crust would be supported by the underground water. Large lakes would have rested on these numerous depressions or pillars. These are the pillars of the earth the Bible refers to:
Job 9:6, “Who shakes the earth out of its place, And its pillars tremble;”
Psa 75:3, "The earth and all who dwell in it melt; It is I who have firmly set its pillars.”
1Sa 2:8b, "For the pillars of the earth are the LORD'S, And He set the world on them.”
Due to the great amount of pressure on this water layer being under 60 miles of the earth’s crust and other forces such as the tidal pumping of the moon, the water began to heat up to the point that it became supercritical water. This supercritical water is still escaping this underground layer into the bottom of the ocean through hydrothermal vents.
Then one fateful day a crack formed in the earth’s crust stretching from the surface to the underground water layer. The extremely pressurized water then exploded out of the crack at supersonic speeds. This caused the crack to spread exponentially in both directions releasing even more water. This crack encircled the globe in a matter of hours tracing what is known today as the mid-oceanic ridge. The mid-oceanic ridge basically forms a circle and runs through every ocean on earth like the seam of a baseball. The mid-oceanic ridge intercepts itself in the Indian Ocean, making a T-formation. This is where one end of the crack terminated by running into the other end of the crack. Since both ends of the crack were travelling at the same speed, we can trace the distance back from this T-formation and determine where the initial crack began.
As the water exploded into the air, it went into the atmosphere and came down around the world as water and snow. Eventually water covered the earth thick enough to stop the water from exploding upwards. But the water level still rose just like when a hose is placed in a pool. Once the water level is high, the spray from the hose is no longer observed but the water level still rises. This is why it says Gen, 7:12 “The rain fell upon the earth for forty days and forty nights.”
But then says Gen 7:18, “The water prevailed and increased greatly upon the earth, and the ark floated on the surface of the water. Gen 7:19, The water prevailed more and more upon the earth, so that all the high mountains everywhere under the heavens were covered. Gen 7:20, The water prevailed fifteen cubits higher, and the mountains were covered. . . Gen 7:24, The water prevailed upon the earth one hundred and fifty days.”
Finally enough water had left the underground chamber that the water underneath could no longer hold up the rock above so that it could escape. So the chamber was closed off trapping the remaining water into its chamber. As the Bible says in Gen 8:2, “Also the fountains of the deep and the floodgates of the sky were closed, and the rain from the sky was restrained; Gen 8:3, and the water receded steadily from the earth, and at the end of one hundred and fifty days the water decreased.”
As the water sprayed outward, it wore away the edges of the crack decreasing the weight of the crust in that area to the point that the mantle rose up forming the mid-oceanic ridge, just like when the earth springs back as an ice cap melts.
This occurred first at the Mid-Atlantic Ridge. As the mantle rose, the North and South American plates separated from the Eurasia and African plates. These plates slid easily on the water below them because supercritical water is nearly frictionless.
Eventually these continental plates hit resistance which caused the plates to compress. As a result, they became shorter and thicker. This thickening caused the continents to rise out of the water leaving the oceans and continents that are observed today. The edge of continents are the edges of the mid-oceanic crack that slid away. This explains why there is a steep drop off at the edge of every continent instead of a gradually sloping towards the bottom of the ocean.
Mountain ranges also formed during this compressing of the continental plates, and they formed perpendicular to the direction of motion of the continental plate. That is why the Rockies and the Andes are on the opposite side of the continent as the Mid-Atlantic Ridge and also why the east coast of Africa is raised. It explains why short mountains such as the Appalachian and Ural Mountains also run from north to south. The formation of other mountain ranges are more complicated due to the formation of the Pacific Ocean.
As the mantle rose in the Mid-Atlantic Ridge, the rock below it moved up to replace the void and the rock below it and so on and so on, until the pacific ocean on the other side of the world sank to fill in the void under it. All of this moving rock grinding against each other caused the rock to melt and produce magma. This is why the ring of fire is around the Pacific Ocean and there are 40,000 volcanoes over a kilometer high on the Pacific Ocean floor.
When weight such as mountains is concentrated on a spinning sphere such as the earth, the surface rotates so that the concentrated mass will spin around the equator. The most massive mountains on earth are the Himalayans. This is why the Himalayans are so close to the equator. They are not on the equator because they are counter balanced by other mountain ranges. Centrifugal force causes the earth to bulge at the equator. As each rotation occurred moving the newly formed Himalayans closer to the equator, the earth’s equatorial bulge formed at a different place each time. This caused the earth’s crust to crack, and this crack continued each time a new bulge was formed. The Ninety East Ridge in the Indian Ocean is this crack. It is a 3,100-mile straight line pointing directly towards the Himalayan Mountains.
The waters eroded away massive amounts of dirt from the sides of the cracks. This mud was then sorted into worldwide layers by the flood waters forming the geological column through a process called liquefaction.
The subterranean waters were rich in minerals from many years of the supercritical water dissolving the rock walls of the underground chambers. These minerals along with the extreme heat and pressure from the flood generated the fossil record. These minerals are also the reason for the saltiness of the oceans.
Much of the water initially froze to form large ice caps leaving evidence that is interpreted as an ice age, so that ocean levels were lower and the world’s continental shelf was exposed. This allowed men to travel to every continent on land bridges. As the ice began to melt, ocean levels and lake levels rose. As the Atlantic Ocean water level increased, it breached the strait of Gibraltar and formed the Mediterranean Sea, probably inspiring the story of Atlantis. Waters draining away from North America left Hopi Lake trapped in the Colorado Mountains. It also eventually overflowed carving out the Grand Canyon. This is unless, of course, you would rather believe the prevailing story that the Grand Canyon was carved by the Colorado River flowing uphill 5,000 ft. for millions of years!