The Biesbosch is one of the last freshwater tidal wetlands in Europe, a 90-square-kilometre maze of creeks, willow forest and reed islands sitting between Dordrecht and Werkendam. It was created by accident — the disastrous Saint Elizabeth's Flood of 1421 drowned a polder of 21 villages and the land never recovered — and is now a national park with beavers, sea eagles, kingfishers and the occasional white-tailed deer.
The best way to see it is by canoe or kayak; you can hire boats at the Biesbosch Museum on Drimmelen-side or at Stayokay Dordrecht, and within minutes of paddling you lose all sight of human infrastructure. There are also self-guided walking trails on the islands, regular boat tours from Dordrecht and a small Biesbosch Museum island with exhibits on the floods, the willow industry that once thrived here, and the ecology of the wetland. Allow at least half a day; longer if you canoe.