The Key West Aquarium is the only public aquarium in Key West, Florida, United States. Built between 1932 and 1934, the Key West Aquarium is one of Florida's oldest aquariums and the first outdoor Aquarium in the U.S.. During the Great Depression, Key West had turned over its charter to the federal government due to the economic disaster that had hit the island. The federal government believed Key West, with its great weather and location, would make a wonderful tourist destination.They were right. This is easy walking distance.