this article, Bronze Age log boats from all across northern Europe look very much the same. Above, one from the Must Farm site in Britain; below, from Denmark. You might think that is unremarkable, because how many way are there to make a boat from a log? But actually these look nothing like log canoes from North America. So perhaps the argument that the similarity of these boats implies close cultural contact makes sense. And anyway I always enjoy it when archaeologists stretch the frame of the argument a little, using artifacts that people generally don't know what to make of.