Museum of Gacka
The Gacka museum is about as you would expect from a museum of a city the size of Otočac. However, the audio guide, which I don't usually find often enough in museums, and the very helpful young lady who took me through the exhibit, made the visit a little better than expected.
There were also a few more surprises. Let's say that the Gacka river is mentioned only in the context of the history and geography of the city of Otočac, although the museum is called the Gacka museum, not the Otočac museum.
In addition to historical exhibits spanning six thousand years, from the ceramics of the Lasin culture to the rifle grenade of the Homeland War, there are also works by local and visiting artists, and the floor below is an ethnographic collection in the form of a representation of a traditional village house.
By the way, do you know that Otočac has the oldest Lidl in the world? Well, I didn't know either until I heard in the museum that Otočac originated on the island, right down there next to Lidl. Otočac was first mentioned as a town around 1300, so I assume that Lidl is at least 700 years old.