Psalm 104 and the Flood:
Was the Genesis Flood Local or Worldwide?
Some say that Psalm 104:5-9 teaches that the Genesis Flood was a local event. They arrive at this conclusion by assuming that the mountains covered by water in this psalm must have been at the time of creation, as opposed to immediately after the flood described in Genesis chapters 6-8: which we are told covered the whole earth -- including the mountains. This assumption of a local flood would mean that the return of Christ will also simply be a local event: as opposed to worldwide, since Jesus compared His return to the Earth, to reign over it to the Days of Noah (Matt. 24:36-39). However, since the Bible teaches plainly (in Rev. 13-22, Isa. 24 and many other places) that the return of Christ will be a global event, a local flood simply doesn't fit; nor does it fit the plain reading of Genesis 7:18-24: where we are told that the Noachian flood covered the whole earth and killed all land dwelling animals and birds -- in whose nostrils was the breath of life -- that were not on the Ark..
Therefore, since this Psalm was written After the Flood of Noah's day, we can say with near certainty that it is speaking of the Genesis 6-8 Flood, rather than of the initial creation of the earth: before God made animals and man, and when the world was "formless and void" or before there even were any mountains: Gen. 1:2.
For those who are interested, Psalm 104:5-9 is quoted below from the New American Standard Version.
5) "He (God) established the earth upon its foundations, so that it will not totter forever and ever.
6) Thou didst cover it with the deep as with a garment; The waters were standing above the mountains.
7) At Thy rebuke they fled; at the sound of Thy thunder they hurried away.
8) The mountains rose, the valleys sank down to the place which Thou didst establish for them.
9) Thou didst set a boundary that they may not pass over, that they may not return to cover the earth."
A local flood view also goes against what we are plainly told in 1 Peter 3:20: where only eight people survived the Noachian Flood, described in Genesis 6-8: see also 2 Peter 4-5. I Peter 3:10-13 also plainly states that the return of Christ will be a worldwide event: meaning that for Jesus to compare His return to the Days of Noah means that the Genesis flood must have been worldwide. Therefore, there is no reason to conclude that Psalm 104 is speaking about any other flood, other than that of Noah's day -- unless one has a preconceived notion about what they want the Scriptures to say.
See also: Scientific Evidence for a Worldwide Flood