The Netherlands is a country that has lost and reclaimed land from the sea over the ages. Islands inhabited as early as the Middle Ages, such as Urk and Schokland, used to lie in the Zuiderzee. Now, they are incorporated in the polder, the reclaimed land and you can actually reach them by car. Closeby, on the old shoreline, a maritime archaeologist discovered the sites of several more medieval lost villages. See the Dutch broadcasting company NOS for the Dutch language article. For an English version, see Dutchnews.nl.
Medieval inhabited artificial mounds in the Low Countries.
Reading about Vikings in the Low Countries.
Blogs by Dutch historian specialized in the Viking Age.
English language site about Vikings in the Low Countries.