Laeso is a small island of some 116 sq km with a population of 2500 in the Kattegat, where sandy soils have been inundated with seawater over the centuries to such an extent that brine from pits dug into the sands has a strength of between 12 % and 16 % of salt.
In the middle ages salt was worked on a large scale. Seventeen medieval salt huts have been excavated, but perhaps as many as two thousand remain to be investigated by archaeologists. The island was owned in the middle ages by the cathedral in Viborg, and paid dues into the cathedral accounts until the early 1950s. Salt production ceased in the first half of the 18th century after all the woodland on the island had been felled.
Since 1991 the Laeso Saltsyderi has produced salt on the island by methods that would have been used in earlier centuries, extracting brine from wells and boiling it in iron pans, based on experience gained in Germany as well as on the results of archaeological excavations. The co-operative operation is commercially viable, attracts some 50,000 visitors per annum, employs ten local people and has a contract to supply high quality salt to the makers of Lurpak butter. Salt is also sold to visitors and to quality restaurants and specialist food shops all over Denmark. This is one of the best places in Europe to witness the methods of making salt depicted by Georgius Agricola that were widely practiced in northern Europe before the Industrial Revolution.
The island museum service has a seaweed farm, with a mill constructed from timbers of wrecked ships, and displays concerned with fishing and the island’s seafarers.