The Naruto Straits are where the Seto Inland Sea meets the Kii Channel. These straits are amongst the three most dramatic in the world, standing alongside the Straits of Messina between Sicily and the Italian Peninsula, and the Seymour Narrows of Vancouver Island in Canada. The difference in height between tides here can reach up to 1.5m, with the currents moving at 15 to 20km/h. This generates whirlpools ranging up to 20m in diameter. You won't want to miss these wonders of nature - some of the largest in the world! The best time to see them is one and a half hours around the high or low tides. Prime viewing season is during tides in spring and autumn.