While not comparable to Seattle's nationally lauded Woodland Park Zoo, the aquarium – situated on Pier 59 in an attractive wooden building – is probably the most interesting site on the waterfront, and it's a handy distraction for visiting families with itchy-footed kids.
The entry lobby instantly impresses, with a giant fish-filled tank called Window on Washington Waters grabbing your attention; background music is sometimes provided by live string quartets. The aquarium houses harbor seals and resident sea and river otters who float comically on their backs. An underwater dome on the lower level gives a pretty realistic glimpse of the kind of fish that inhabit the waters of Puget Sound, and the daily diver show here is probably the best of the aquarium's live events. For kids there are plenty of hands-on exhibits, including a pool where you can stroke starfish and caress sea urchins.