Size isn't everything, but standing in front of a massive ocean tank does provide a feeling that is hard to replicate by smaller exhibits. In the following, I've tried to list all aquarium fish tanks that contain 4 million liters (1.1 million gallon) or more. There are a number of aquariums with tanks that come close, but I had to place the limit somewhere and if lowering the border to 3 MM l. (0.8 MM gal) the list would be too long. This is about single tank only; not combined volume of all tanks at the aquarium! Two of the listed tanks do periodically have dolphins mixed with the fish, but tanks aimed at mammals are excluded. The numbers I've provided are only approximate because of conversions between units and that even a small differenece in water level can result in quite big differences in volume. THE GIANTS: * Georgia Aquarium (USA): 24 MM l. (6.3 MM gal). * Chime-Long Ocean Kingdom (China): 22.7 MM l. (6 MM gal). * Marine Life Park (Singapore): 18 MM l. (4.8 MM gal) * Atlantis–Lost Chambers (United Arab Emirates): 11.5 MM l. (3 MM gal). * Dubai Aquarium and Underwater Zoo (United Arab Emirates): 10 MM l. (2.6 MM gal). * Cube Oceanarium (China): 10 MM l. (2.6 MM gal). * Okinawa Churaumi Aquarium (Japan): 7.5 MM l. (2 MM gal). * L'Oceanogràfic (Spain): 7 MM l. (1.8 MM gal) Notice: When Chime-Long Ocean Kingdom opened it was recognized by Guinness World Records as having the largest tank in the world. I suspect there are two possibilities: Either they're wrong and Georgia's tank is larger. Alternatively the volume provided by Georgia includes the rear holding pool (see attached map) or water volume in pumps (a lot in big tanks), which possibly would make the actual main tank smaller than Chime-Long's. Regardless, Chime-Long's record for largest acrylic viewing window was beaten a month ago when Cube Oceanarium opened. THE BIG ONES: These 16 tanks are all 4–6 MM l. (1.1–1.6 MM gal) and are listed by geography, not relative size: * USA: Monterey Bay Aquarium; Shark Reef at Mandalay. * Denmark: Den Blå Planet–National Aquarium; Nordsøen Oceanarium. * Norway: Atlanterhavsparken. * Portugal: Lisbon Oceanarium. * Spain: Aquarium Finisterrae. * UK: Blue Planet Aquarium; Deep Sea World. * Turkey: Antalya Aquarium; TurkuaZoo. * China: Nanjing Underwater World; National Museum of Marine Biology and Aquarium–Taiwan; Ocean Park Hong Kong. * Japan: Osaka Aquarium Kaiyukan. * South Korea: Aquaplanet Jeju. There are three additional that I suspect belong in "THE BIG ONES", but I'm not sure and I've been unable to find good info on their exact sizes: Istanbul Aquarium (Turkey), Yokohama Hakkeijima Sea Paradise (Japan), and Aquaplanet Yeosu (South Korea). I would be interested in knowing if I missed any in the list.