The Spreewaldmuseum in Lübbenau is a useful grounding stop before or after you take to the canals. It explains the region through boats, tools, household objects, traditional dress, crafts, and the everyday adaptations that made life possible in a wet, forested landscape split by waterways.
It is especially good if the Spreewald has otherwise started to feel like a postcard of punts and pickles. The museum gives the landscape a human story, including Sorbian culture and the small economies that grew around the marshes. Pair it with the old town, the harbour, and one of the quieter canal routes.