Cycle along the Afsluitdijk between North Holland and Friesland. With 300,000 visitors per year, the Afsluitdijk is one of Holland's most popular water It also changed the saltwater Zuiderzee into the freshwater IJsselmeer. However, make sure that you have a guide, or that you are well aware of the dangers involved.
Links:
Tyler-Tailor the Warthog Without a Tail : A Story of Loss, Grief and Growth
Mythologica, 4 Bde. in 5 Tl.-Bdn. : (Nr.167-170) free