13,000 years ago you could have walked from Scotland to Finland. The North Sea wasn’t there yet.
That capability had to have been developed earlier during the period of maximum glaciation ~ just about the time they figured out how far they could hunt seal along the Southern edge of the winter sea-ice (which turned out to be all the way to America).
Love those spear points ~ did that guy say "arrow head"? There were no bows, no arrows, so no "arrow heads" ~ just "spear points" at that time.