What passes for a small and compact aquarium is in fact an actual ecosystem with 250 species and 5000 fishes living in the Otaru aquarium. Upon arriving, you will find yourself staring at a very scenic outdoor and then comes the visit which will take you about 2.5 hours. Colorful fishes from the North Sea populate the pools while dolphins, sea lions and penguins make quite a show.
To get there, just take the bus from the city, it is a very convenient ride (about 26mn from town) and you can bring along your family and kids. They will definitely love it, especially the part where they can get to touch the cute aquatic creatures.
The first shows start in the morning with seal feeding, then come the dolphins and the penguins parade. This last part is definitely a must see, the penguins will tour the place letting everyone time to take some stunning pictures.
In case you find yourself thirsty or hungry you can stop by the cafeteria and enjoy a bit of calm before continuing your visit.