Due to the very high tidal difference of the Seto Inland Sea and the complex topography of its seafloor, the surface of the sea around the Shimanami Kaido is roiled by rapid currents that flow like a river, creating a constantly changing pattern of whirlpools on the surface when the tide turns. Fast motor boats leave from the north and south of Omishima Island, taking you right into the maelstrom to experience this remarkable natural phenomenon at close quarters.

Noshima Cruise
The boat that departs from the northern end of Omishima near the Murakami Suigun Museum sails around the island of Noshima, once a fortress of the Murakami Suigun maritime clan. You can still see the outlines of the fortifications. The rapid currents that race around the island with a roaring sound were an important part of its defenses. The boat also visits Funaori Seto, ‘shipwreck channel’, a passage between two islands that was known to break ships in half in olden times. A recorded announcement in Japanese explains the various sights. These reasonably-priced tours are an excellent way to experience the mysteries of the Inland Sea and to enjoy some unusual sights from a different perspective. Up-close, the tidal currents and whirlpools are truly impressive.

Kurushima Straits Cruise
The boat departing from Iki-Iki-Kan at the southern end of Omishima sails into the whirlpools that form under the Kurushima Straits Bridge, and around the various islands that were inhabited by the Murakami. It also sails into the Kurushima Dock, taking you close to some huge, shiny ships. The sights are explained by a young lady on a mic. At the end of the trip, she sings a rather lovely song about a bride who goes to live on one of the islands.