The Naruto Whirlpool consists of numerous, small and large, whirling currents arising in the Naruto Strait between the town of Magosaki Naruto and Awaji Island.
The currents occur because of the  different tide level between Seto Inland Sea and the open sea (the Pacific). It gets biggest when the difference in tide level is the greatest in spring and autumn. The whirlpool moves at20 km per hour and its maximum diameter reaches 20 meters.
The whirling currents interlace and run making a roar like thunder; it is difficult to describe the scene with words other than tremendous.
The whirlpools appear in generally the same place.  The current whirls in different places, but as it disappears, a new current is generated.
Its magnificence could best be described as a ‘waterfall in the sea’ and it is one of the most impressive three major currents in the world.
Ou-naruto Bridge, 1,629 meters long, was built to traverse the whirlpool in 1975, and it makes an appealing view  of natural and artificial beauty combined.