The Gdynia Aquarium sits at the base of the Southern Pier and is operated by the National Marine Fisheries Research Institute. Its strongest section is the Baltic wing — proper, well-labelled tanks of the species most visitors will never see despite swimming next to them: cod, eels, plaice, the few seals that live in the eastern Baltic.
There are also tropical tanks, an Amazon section, and the obligatory shark tank. The aquarium is smaller than equivalents in major European capitals — allow 90 minutes — but the research-oriented framing of the displays makes it more interesting than most. Combined ticket with the museum ships available.