Since there are no "holes" in the account of the flood, your humor is feckless. The water did not "go away". The mountains were formed towards the end of the flood, just before the "waters receded".
From a previous post on the flood and mountains:
The assumption is made that the mountains we have today are the ones that were pre-flood. Not necessarily so. Prior to the flood, there were no mountains or very low ones. Why? Mountains had no meaning in God’s original creation since they principally are for water storage (snow to water runoff). Genesis 2:5 states that it had not rained on the earth (sound fantastic, hard to believe?). In fact, the rain did not come until the flood, about 1700 years after the creation. Genesis 2:6 states, "but streams came up from the earth and watered the whole surface of the ground". Further, Adam and Eve were unclothed (Genesis 3:10), year round. Because of the rivers cited (Tigris and Euphrates) we can surmise that the Garden was somewhere in Iraq to Northern Israel. That terrain is very inhospitable during the summer (heat) and winter (cold). Hardly nudist colony conditions.
But, after the flood, God changed the behavior of the atmosphere. No more running around in the buff. And “heat and cold, summer and winter” were introduced post-flood (Genesis 8:22). The creation of the mountains, for the most part, took place while the ark was safely "bobbing" around on the surface of the water - the occupants completely unaware of the tectonic activity below. Thus, the "receding waters" were coincident with the creation of the mountains as God also returned the water back to the "fountains of the deep". It has been demonstrated by scientists that the content of fresh water in the Earth’s mantle is greater than the amount of fresh water above ground.
To close the loop on the "appearance" of the mountains, in the future, God will return the earth to the state it once was - low hills and an atmosphere in which it does not rain, nor is there need for snow, and no heat nor cold. This occurs towards the end of the seven year tribulation, just prior to Jesus establishing His 1000 year reign on earth. This is what happens to the mountains - all of them - around the earth: "The seventh angel poured out his bowl into the air, and out of the temple came a loud voice from the throne, saying, 'It is done!' Then there came flashes of lightning, rumblings, peals of thunder and a severe earthquake. No earthquake like it has ever occurred since mankind has been on earth, so tremendous was the quake ... Every island fled away and the mountains could not be found." (Revelation 16:17-18,20).
The clues are all there in the Bible for a reasonable answer to your question. And, clearly, it was a world-wide flood. Not simply local, which does not make sense, and which contradicts what the Bible states, "So God said to Noah, 'I am going to put an end to ALL people, for the earth is filled with violence because of them. I am surely going to DESTROY both THEM and the EARTH.'" (Genesis 6:13).