Mazatlan Aquarium (Acuario Mazatlán)
This aquarium is a bit of a cobbled-together affair with displays in multiple buildings spread throughout the grounds. It contains more than 300 species of fish, plus crowd pleasers like porpoises, rays, turtles, and sharks. If you pony up extra money, you can swim with those sharks or feed them yourself.
This is a varied attraction for families, with tropical birds doing tricks in an open theater and in another area, trained sea lions jumping and splashing. There are play areas for the kids and a restaurant on site with reasonable prices. You can also tour botanical gardens and a small zoo, the highlight being several aviaries with colorful birds overhead.