Naruto whirlpools

The Naruto whirlpools are tidal whirlpools in the Naruto Strait, a channel between Naruto in Tokushima and Awaji Island in Hyōgo, Japan. The strait between Naruto and Awaji island has a width of about 1.3 km. The strait is one of the connections between the Pacific Ocean and the Inland Sea, a body of water separating Honshū and Shikoku, two of the main islands of Japan. The tide moves large amounts of water into the Inland Sea twice a day and also removes large amounts of water twice a day. With a range of up to 1.7 m, the tide creates a difference in the water level of up to 1.5 m between the Inland Sea and the Pacific. Due to the narrowness of the strait, the water rushes through the Naruto channel at a speed of about 13–15 km/h four times a day, twice flowing in and twice flowing out. During a spring tide, the speed of the water may reach 20 km/h, creating vortices up to 20 m in diameter. ()