- 1 Biesbosch National Park. The Biesbosch or Biesbos is the name for a number of river islands, sandbars and mudflats in the Dutch provinces of North Brabant and South Holland. It is situated between the rivers Upper Merwede and Amer and bisected by the artificial river Nieuwe Merwede. It is a tidal with creeks, willows and tidal forests. In 1994 the area was granted with the status of national park. The park has many recreational opportunities but is also used for storage of drinking water. There are three visitor centers; in Dordrecht, in Drimmelen and Werkendam.