Maretarium opened on the shore of Sapokanlahti bay in 2002 and offers something genuinely distinctive: an aquarium focused entirely on Finnish fish, presenting the species that live in the country's rivers, lakes, and coastal waters rather than imported tropical specimens. For visitors who have been swimming in Finnish lakes without a clear sense of what was swimming alongside them, the experience is quietly revelatory.
The tanks are spacious and naturalistic, with good lighting and informative displays in Finnish, Swedish, and English. Highlights include the large river tank — full of salmon, sea trout, and pike — and the coastal tank that replicates the brackish-water ecosystem of the Gulf of Finland. Maretarium is compact enough to see comfortably in two hours, and is well suited for families with children. The location on the bay, a short walk from the city centre, makes it easy to combine with a harbour walk.