Footage from the scene shows the swine swimming for the shore with its snout and ears poking above the water.
Shouts of "laufen!", meaning run in German, are heard from various people on Schonhagen Strand, though one woman on the edge of the shore can be seen calmly pointing out the approaching boar to a young girl.
A man was seen to strike the boar on its side with a spade as it turned towards him after emerging from the sea.
Seemingly unfazed, the boar continued up the beach causing pedestrians to clear the way as it sprinted through.
Wild boar are known to be able swimmers. There were reports last year of a herd of boar swimming several miles across the Malacca Strait from Indonesia to Malaysia and terrorising farmers upon arrival.
In 2019, Danish authorities built a 42-mile fence spanning the German border, not far from the beach at Schonhagen, in order to keep wild boar out.