Just a refresher. De Biesbosch was created as a result of human activity and the force of nature. Before the 15th century, the area was a marsh with creeks and small rivers. Dike building and land reclamation drastically changed the landscape. During the Sint-Elisabethflood in 1421, the dikes broke and the sea pounded on the land and villages. This created a large tidal area. This marked the beginning of the formation of the Biesbosch as we know it today. In the centuries that followed, people further changed the area, including the construction of dikes and locks. The result is a vast freshwater tidal area with unique flora and fauna.