It's been theorized that, at the world's creation, there was a single continent like the so-called pangea. No need for any of mankind to travel across oceans to visit one another. Also flatter. The highest "mountain" being no more than a couple of thousand feet, hills really. The forces unleashed by the flood split the super continent into what we see today. The ensuing movements of the tectonic plates caused the high mountains as they are today. This theory fits with the flood narrative and known science, AFAIK.
This idea doesn't originate with me, BTW.