The Shedd Aquarium is located on the Museum Campus at 1200 S Lakeshore Drive. I went on a free day which almost all of the museums in Chicago have for residents of Chicago/Illinois. These days tend to be very packed for the museums. The free days are for the basic exhibits only which means for the Shedd Aquarium you don’t get to see as many of the animals or fish. You do get to see their beautiful Caribbean Reef which can be found in the rotunda. It is 90,000 gallons and you can watch as they send a diver in to feed and talk about the creatures in the reef around 2pm.
With the basic pass you can also see bugs, birds, reptiles, amphibians and all sorts of fish including some seahorses. The aquarium also houses jellyfish, penguins, sharks and larger mammals. In order to see these it can get a bit expensive. From May through October you can pet the sting rays. Certain tickets can be bought ahead of time online that may make it faster to get through lines on busy days, but general passes have to be purchased at the Aquarium.