In October 1998, the Great Barrier Reef complex opened comprising a tropical touch pool, a live coral cave, coral atoll, two circular gateway displays and a massive Great Barrier Reef oceanarium. Over 6,000 animals are housed in the oceanarium which contains 2.6 million litres (572,000 imp gal, 687,000 U.S. gal) of water pumped from Darling Harbour, filtered and heated before it flows into the Oceanarium and adjoining display tanks. The water is kept at a constant temperature of . The Oceanarium is long and wide, with a total area of about and a water depth of . The final exhibit is a reef theatre where activity in a coral canyon can be observed through a window and in thickness.