"Naruto whirlpools" is a natural phenomenon formed by intense tides in the "Naruto Strait" sandwiching Awajishima and Naruto City due to the ebb and flow of the tide between the Pacific Ocean (Kii Channel) and the Seto Inland Sea. At the time of "high tide", there is a whirlpool on the Awajishima side and on the Naruto side at the time of "low tide", but the tide boat goes to the place where the whirlpool can be formed, so you can see the whirlpool near you. At the time of spring and autumn, its diameter can reach about 20m, and it is said to be unparalleled in the world.