Not really my point. If you are paddling your way to a new world you most likely are hugging the coastline. That ancient coastline is currently 400 feet under water. And can be quite a distance offshore from our current coastline. So they could have wandered far and wide but still be in an area now inundated with sea water.
Congratulations and welcome to the fold.
Yes, island hopping might have been an option back in the day when the Kurile and Aleutian chains occupied a more temperate zone than is currently the case . . . or even might have been fewer and larger islands.