This tank isn't for the everyday hallway, or living room centre piece. What your looking at is 6 storey high, has water enough for a whale to live in maybe two even. This isn't a science experiment, it's a breathtaking centre piece for The Radisson SAS Hotel in Berlin. Its 25meters (80feet) high 11metres in diameter , contains 1 million liters (260,000 gallons) of salt water, and is home to 2,500 fish (56 species in all). There's also a glass elevator that goes up the middle if you want to swim with the fishes without getting wet. Two full time divers are tasked with keeping the residents healthy and happy, which might sound like a fun job, but I bet they have to keep the glass clean as well.

In addition to being the largest cylindrical fish tank, the Aqua Dom is also the largest acrylic glass cylinder in the world, with a diameter of 11 meters. The whole thing cost nearly 13 million euros back in 2003, but you can book a fishtank-view room in the hotel for considerably less than that (about 260 euros on a weekend).

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