Awaji Island's vortex is the largest in the world.

Below the Onaruto Bridge that connects Awaji Island and Shikoku, is one of the world's three greatest currents, the Naruto Strait, which is pushed against it like a waterfall. The speed of the current can go as fast as 10.6 knots (about 20 km/h), which makes it the third fastest in the world.
The currents that run through the Pacific Ocean and Seto Inland Sea collide with one another here at the Naruto Strait, creating a "vortex." Due to the effect from the shapes of the costal lines and the sea floor, the diameter of the vortex becomes approximately 30 m, which is the largest in the entire world.
The vortex roars with energy and signifies the power of the natural world.
Currently, the "Naruto Vortex" is being promoted to be registered as a World Natural Heritage site.

Awaji Island's vortex is the largest in the world.

How do vortexes form?


Branches Off

The current that enters the Kii Channel branches off in two directions to the Naruto Strait and the Osaka Bay.


Reaches the Naruto Strait

The current that went to the Osaka Bay will take 5-6 hours traveling through the Akashi Strait and circle around Awaji Island, reaching the Naruto Strait.


The difference in height of the sea surface causes the current to rush in.

When the current that moves through the Osaka Bay reaches the Naruto Strait and it becomes high tide, the current that traveled to the Naruto Strait first passes through as the low tide. At this point, the sea surfaces of Harimanada (high tide) and the Kii Channel (low tide) has a gap in height. The Harimanada side has a higher sea level, and it pushes towards the Kii Channel water at a lower sea level. With the other conditions, such as the shapes of the sea floor, it causes the vortex. During particularly large currents, the gap can be as wide as 2m. The vortex of the Naruto Strait has a current of 20km and a vortex diameter of 30m, making it the world's largest vortex.

How do vortexes form?


Activities on Awaji Island

On Awaji Island, there are many activities aside from the vortex. We hope you'll enjoy your experience on Awaji Island.

  • Fishing


    Awaji Island is full of great spots for fishing. Different fish can be caught during different seasons. There are shops that rent out fishing equipment and bait, so you don't need to bring your own.

  • Bicycling


    On Awaji Island, there are roads following the coastline for bicycling with a great views. Bicycles can also be rented.

  • Parasailing


    Parasailing is a marine sport where you attach a parachute to your body and are then drawn by a boat while you float up into the air. Great even for beginners.

  • Loquat Picking (Fruit Picking)

    Loquat Picking (Fruit Picking)

    Loquats are a sweet and juicy fruit. You can pick them off of trees with the loquat picking activity. There are also other fruit picking spots around the island.

  • Incense Making

    Incense Making

    Awaji has the highest production volume of incense in all of Japan. You can take a tour of the factory or participate in making incense in a workshop.

  • Stained Glass

    Stained Glass

    Make your own accessory at the stained glass workshop.

  • Play with Dolphins

    Play with Dolphins

    Awaji Janohire Outdoor Resort has the Dolphin Farm with many courses where you can play with dolphins. You can simply touch and play with dolphins or even swim with them. There is also a course where you can experience training dolphins.