North America is the northern continent of the Americas, situated in the Earth's northern hemisphere and in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific Ocean; South America lies to the southeast.
North America covers an area of about 24,709,000 square kilometers (9,540,000 square miles), about 4.8% of the planet's surface or about 16.5% of its land area. As of July 2008, its population was estimated at nearly 529 million people. It is the third-largest continent in area, following Asia and Africa, and the fourth in population after Asia, Africa and Europe.
You finde bigger Aquarias and Zoos in Bermuda (1 Zoo), Canada (2 aquarias & 4 zoos), Dominican Republic (1 Aquarium), Mexico (2 aquariums & 6 zoos), Trinidad & Tobago (1 Zoo) and the USA , (32 Aquarias, 1 Bird Park, 1 Terrarium and 58 Zoos). Of these the biggest Zoo is the one in Omaha/Nebraska in the USA. The Biggest Aquarium is the one in Chicago/Illinois in the USA, being the Worlds Largest Collection of living species World Wide.
These Zoos have free entrance:
Chicago Zoo, Illinois, USA
Madison, Wisconsin, USA
Mexico City, Mexico
St. Louis, Missouri, USA (except Children's zoo)
San juan de Aragon, Mexico
Washington Zoo, District of Columbia, USA
Woods Hole, Massachusetts, USA