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 20km/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 costal lines and the sea floor, the diameter of the vortex becomes approximately 30 m, which is the largest in the entire world.
