Big O (ビッグ・オー, Biggu ō) is a centerless non-rotating Ferris wheel at Tokyo Dome City in Bunkyo, Tokyo, Japan. Big O has a diameter of 60 metres (200 ft).[1] Tokyo's largest roller coaster, the 130-kilometre-per-hour (81 mph) Thunder Dolphin, passes through the centre of the wheel.[2]