The Knardijk is an inner dike that serves as a boundary between Eastern and Southern Flevoland. It was originally constructed as the southern outer dike of the polder Oostelijk Flevoland, which was the first phase (1957) in the development of the larger Flevoland polder. Because Southern Flevoland was completed considerably later (1968), the Knardijk remained a full-fledged outer dike for a long time, serving as the separation between the new land and the open water in the southern compartment of the IJsselmeer. The Knardijk is named after the former shallow area, the Knar, in the Zuiderzee.

For ten years, the Knardijk provided protection to Eastern Flevoland against the IJsselmeer. But since the reclamation of Southern Flevoland, the Knardijk no longer has a direct water retentive function. The dike is now a sleeper dike. If water were to flood one of the two polders, the Knardijk would protect the other polder from the consequences.

The length of the Knardijk covers over twenty-three kilometers of the total ninety-kilometer dike that had to be constructed at the time. The dike makes for a nice cycling route between Zeewolde (starting point De Biezenburcht - cycling junction 23) and Lelystad.