The small town of Naruto faces the island of Awaji across the Naruto Strait, which is spanned by a huge suspension bridge. The unique topology of the Seto Inland Sea causes huge whirlpools to appear in the Strait under the bridge. You can take a boat ride out to experience the phenomenon directly, or look down on it from the glass floor of the bridge called Uzunomichi.
Depending on the tides, the whirlpools occur roughly every six hours and you can generally see them once in the morning and once in the afternoon for an hour or two. The size of the whirlpools varies, according to the intensity of the tides. Tides are larger in summer than in winter, and spring tides are the largest. The best time to see the whirlpool every day is shown here.
Another place to see the dramatic tidal phenomena of the Inland Sea is the Geiyo Islands that make up the Shimanami Kaidō.
Name in Japanese: 鳴門の渦潮
Pronunciation: naruto no uzushio
Address: Fukuike-65 Narutocho Tosadomariura, Naruto, Tokushima 772-0053