Real: that is entirely reasonable, and I would agree.
World-wide, it cannot have encompassed the whole world in the modern sense. “Whole world” is frequently used for “whole known world”, like in Isaiah 23:17 and Luke 2:1. The passage can reasonable be interpreted to refer to “all the area known to those who survived it”, and if this were a low, flat area, the mountains/high hills need not be overly tall. A flood covering the entirety of earth’s surface in water would produce a produce a noticeable geological and biological signal of a type that has not yet been found.