Natural phenomenon not well known in the world but very impressive, the Naruto whirlpools called "Naruto No. Uzushio" 鳴門の渦潮 are caused by the interaction between the tidal inside Seto Sea and the Pacific Ocean and the narrow strait of Naruto (1340 meters wide). These whirpools can measure up to 1.7 meters deep and 20 meters in diameter. What makes this whirlpool of Naruto one of the largest in the world. The hours of tides are indicated on the site Naruto no Uzushio.
How to explain this phenomenon?
Tides are the source of this incredible phenomenon. Indeed, it is tides which are responsible for the difference in height of the water level of seas and oceans. Knowing that the tides of the Seto Sea and the Pacific Ocean are not synchronized, the water level of one rises when the other goes down. The difference between the two water levels may be up to 1.5 meters by hours of the day. When the height of the water level decreases, it creates a very strong current. The current speed can reach up to 20 km/h. In addition, the strait is not very large, so it creates barriers to the marine currents and therefore, one of two marine currents will slow speed compared to the other. Thus the encounter between a fast sailor updraft and a slow sailor downdraft creates the whirpool phenomenon that is observed in Naruto.
How to witness it ?
There are several ways to watch Naruto Whirlpools :
- The Ōnaruto Bridge : suspension bridge of 41 meters in height (at car and pedestrian passage level) and 1629 meters in length connects the island of Shikoku to Awaji Island. There is a pedestrianway named Uzunomichi Walkway in the south of the bridge. The entrance is near the Ōtsuka Museum of Art and the access to the bridge cost 510 yen. You will be able to observe the marine whirpool from above.
Entrance Fee : 510 yens
- The boat - cruise: Some companies offer 30 minutes Cruises to observe marine whirpools. The pier is located in southwestern of Ōnaruto Bridge. These boats go under the Ōnaruto Bridge, around and in the whirpools. Some boats (company AQUA EDDY) allow you to see what's going on under the water, even if it costs a bit more, because the boats have windows at the ship's hold (this is the type of boat we took). So you can observe this phenomenon closely.
Cruise Fee : 1500 à 2400 yens
- The Naruto Park , Naruto Koen 鳴門公園 : There are several spots in the park along the Ōnaruto Bridge where you can see for free the whirpool from far.
Entrance Fee : Gratuit
These whirpools are truly spectacular and if you have the opportunity to go to Tokushima, do not hesitate to go see this natural phenomenon. You can choose the way that suits you best :)