[Swirl]

my favorite hypothesis is that most of the water was subterranean prior to the great flood. Perhaps water was available from wells and springs but not rain. Then something happened to release this water.
This would explain the rainbow 1st occurrence as well.

[mountn man]

https://news.northwestern.edu/stories/2014/06/new-evidence-for-oceans-of-water-deep-in-the-earth