It Must Have Been A Dream!: Shikoku - The Churning Naruto Whirlpools

At the deep harbour near Sentosa one day, an empty drink cup toppled over the edge of the bridge. Surprisingly, it neither sank nor was carried away by the current.

Instead, it was sucked into the current and spun wildly round and round on the surface of the water.

Thus began my fascination with whirlpools.

In Japan, on a long suspension bridge spanning the width of the narrow straits of the Seto Inland Sea, lies a churning mass of water. The Naruto Whirlpools occur along the Shikoku coast of the Naruto Strait, and are created by the large volumes of water moving between the Seto Inland Sea and the Pacific Ocean between high and low tide, combined with the unique underwater geography of the narrow strait.

Due to the narrowness of the strait, the water rushes through the Naruto strait at a speed of about 13-15km/h four times per day, twice flowing in and twice flowing out. During the spring tide, the speed of the water may reach 20km/h, creating whirlpools of up to 20m in diameter. The current in the strait of the Naruto whirlpool is the fastest in Japan and the third fastest in the world after the Saltstraumen (Norway) and the Old Sow (Canada) whirlpools.

When's The Best Time?

According to the change of tides, the whirlpools occur roughly every six hours and can typically be seen once in the morning and once in the afternoon for an hour or two. The whirlpools vary in size, depending on the intensity of the tides. They tend to be larger in summer than in winter, and are largest during spring tides, which occur every two weeks. Under ideal conditions, whirlpools of up to 20 meters in diameters can be observed.

The best view of the Naruto whirlpool can be observed when:

In the spring season (end of March till end of April), or fall,
At high tide and low tide occurring twice each day (best is 1.5 hours before and after the high tide) which is caused by combined effects of the gravitational forces exerted by the Moon and the Sun, and
When the Earth, Moon and Sun are approximately aligned which occurs approximately twice a month at the full moon and new moon.

The Uzusio site indicates the best times to see the whirlpools up to 6 months ahead.

http://www.uzusio.com/siomi/siomi.php

Times printed in red indicate good times to see strong whirlpools. 年 means year. 月 means month.

(Sample Calendar)

By Bridge

From Naruto Station, I take the bus to Naruto Park (Y310). Following the advice given on the Japan Guide pages, I bought the combination ticket and decided to first try out the bridge view.

External observation deck...

The Uzu no Michi is an enclosed walkway that extends under the Onaruto Bridge and overlooks the whirlpools.

It's quite exciting to walk with empty space on both sides of you
and the sea wind howling in the background...

At 45 meters above, the whirlpools below can be seen through glass windows set in the floor.

Several windows on the floor so no need fight with anyone to fight a good photo angle...

Can even see boats passing by below you.
You get kinda feel like Zeus in the movie Jason & The Argonauts...

By Boat

As the whirlpools are best viewed from a higher vantage point, it is recommended to take a "Wonder Naruto" boat tour which offers the best views from its upper first-class deck at an additional charge.

The Wonder Naruto Boat...