Sydney Aquarium is a public aquarium located in the city of Sydney, New South Wales, Australia. It is located on the eastern (city) side of Darling Harbour to the north of the Pyrmont Bridge.

The aquarium contains a large variety of Australian aquatic life, displaying more than 650 species comprising more than 6,000 individual fish and other sea and water creatures from most of Australia's water habitats.

Its key exhibits are a series of underwater, see-through, acrylic glass tunnels where sharks swim above visitors, and recreation of a Great Barrier Reef coral environment.

The Sydney Aquarium was opened in 1988, during Australia's bicentenary celebrations, and is one of the largest aquariums in the world. It is regarded as one of Sydney's premier tourist attractions with over 55% of its visitors each year coming from overseas. A crocodile exhibit is being planned for 2008.

In 2006, Sydney Wildlife World opened next to Sydney Aquarium, which is owned by the same Sydney Attractions Group.