Emaar Aquarium & Underwater ZooOn the Asian side in Üsküdar, with over 5,000 animals, a long acrylic tunnel, a giant Pacific octopus, electric eels and Humboldt penguins. Inside Emaar Square Mall, and easy to combine with a Bosphorus crossing to take in both continents in a day. Free below 3.
ViaSea Aquarium (Tuzla)A compact mall-based aquarium at ViaPort Marina in Tuzla on the far Asian side, with exhibits at toddler height, an underwater tunnel with sharks, and reptiles and turtles. Doable in about 45 minutes and good for younger children, near Sabiha Gökçen airport. Free below 3.