This was the end of a long dam, leading the "Zwolse Diep" into see. Here passed the shipping from the Vecht and Zwarte Water rivers into sea, carrying German Bentheimer stone and peat for heating from Overijssel and Drenthe over the Zuiderzee to Holland, Baltic timber by seagoing ships to the sawmill in Zwolle. There were also several shipyards in Zwartsluis, Hasselt and Zwolle.
Before the building of the Afsluitdijk, 1927/33, there was tidal water as far as Zwolle.