The Shedd Aquarium is not the biggest aquarium. The title of the largest aquarium in the world goes to the Georgia Aquarium in Atlanta, USA. The Shedd Aquarium is, however, the largest indoor aquarium in the world.
The Georgia Aquarium opened in 2005 and houses over 100,000 marine animals. It is located on 22 acres (9 hectares) and has a total water volume of 10 million US gallons (37,854 cubic metres). The Shedd Aquarium was built in 1930 and occupies 5 acres (2 hectares). Its total water volume is only 2.5 million US gallons (9,462 cubic metres).
So while the Shedd Aquarium may not be the biggest aquarium by land or water volume, it is certainly one of the most impressive – especially given that it was built nearly 80 years ago!