Naruto Strait lies between Magozaki on Oge Island in Naruto, Tokushima Prefecture, on the northeastern edge of Shikoku, and Monozaki on Awaji Island in Minami-Awaji, Hyogo Prefecture. Known in Japanese as Ōnaruto, the strait forms an important maritime passage connecting the Harima-nada Sea, part of the Seto Inland Sea, with the Kii Channel leading to the Pacific Ocean.
The strait is famous for the spectacular Naruto whirlpools, created by powerful tidal currents flowing through its narrow waters. Its dramatic natural scenery has earned it a place among Japan’s 100 Landscapes, a selection of the country’s celebrated scenic destinations.
At its narrowest point, Naruto Strait measures approximately 1,340 meters across between Monozaki on Awaji Island and Magozaki on the Shikoku side. Several small islands and underwater features lie near this passage. Hadaka Island is approximately 200 meters from Oge Island, while the rocky outcrop of Nakase lies about 300 meters from the Awaji Island side. These locations are associated with the bridge supports of the Ōnaruto Bridge.
The seabed in the center of the narrow passage forms a deep V-shaped channel reaching approximately 90 meters below the surface. Deeper depressions known as kaifu lie to either side, reaching depths of around 160 meters to the south and 200 meters to the north. This underwater terrain contributes to the complex currents that make the strait both fascinating and challenging to navigate.
The Naruto whirlpools are created by the powerful tidal currents that flow between the Pacific Ocean and the Seto Inland Sea. Tidal water entering from the Pacific divides in the Kii Channel. One current flows toward the southern side of Naruto Strait, while another travels through Osaka Bay and the Akashi Strait into the Harima-nada Sea.
The difference in water levels between the two sides of the strait can reach approximately 1.5 meters. As large volumes of water pass through the narrow channel, strong currents develop and generate swirling vortices downstream of the narrowest section.
The largest whirlpools can reach approximately 15 meters in diameter. Their size and intensity vary with the tides, so the spectacle changes throughout the day. The powerful movement of the water makes Naruto Strait one of Japan’s most remarkable natural attractions.
Special sightseeing boats operate from both the Awaji Island and Naruto sides of the strait, allowing visitors to observe the whirlpools from close range. Seeing the swirling water from a boat provides a vivid sense of the strength and speed of the currents.
The Ōnaruto Bridge, which connects Awaji Island with Shikoku, offers another way to experience the strait. Its pedestrian observation walkway, known as Uzu no Michi or the Whirlpool Walkway, allows visitors to look down toward the water from above.
From this elevated viewpoint, the powerful currents and swirling patterns are visible beneath the bridge. The combination of the whirlpools, open sea, and impressive bridge structure makes this area a highlight for nature lovers and photographers.
The hills, forests, coastline, and islands surrounding Naruto Strait are valued for their scenic beauty. In 1931, the area encompassing Naruto Park and its surrounding hills, wooded slopes, coastlines, and islands was designated a National Place of Scenic Beauty in Japan.
In 1950, the area was also incorporated into Setonaikai National Park, recognizing its importance as a natural landscape and a destination for visitors. The protected surroundings offer opportunities to appreciate the strait from different viewpoints as well as to explore the wider coastal scenery.
The Ōnaruto Bridge opened in 1985, providing a road connection between Awaji Island and Shikoku. Today, it serves as an important part of the transportation route linking the islands, although it is a road bridge rather than a general-purpose pedestrian crossing.
Ten years after the bridge opened, in 1995, the remaining ferry service operated by Awaji Ferry Boat between Anaga on Awaji Island and Kameura on the Tokushima side was suspended and subsequently discontinued. As a result, crossing the strait with mopeds and similar small motor vehicles by ferry was no longer possible.
West of the main Naruto Strait lies Little Naruto Strait, also known as Konaruto or the Muya Strait. This narrower waterway separates the main island of Shikoku from Oge Island and Shimada Island.
Little Naruto Strait extends for approximately 8 kilometers and narrows to around 110 meters at its tightest point. Although less famous than the main strait, it is another distinctive feature of the waterways around Naruto.
Naruto Strait is recognized as one of Japan’s three major maritime passages known for their difficult navigation conditions. Although it forms part of an important shipping route, the navigable channel is only about 500 meters wide, and strong tidal currents can make passage difficult.
The Japan Coast Guard’s Tokushima office has warned vessels to wait for slack water when conditions require it. Between 2002 and 2006, a total of 15 marine accident cases were formally adjudicated in connection with the strait, including eight that occurred directly beneath the Ōnaruto Bridge. Many incidents involved vessels being pushed off course by powerful currents or losing the ability to maneuver safely.
These conditions underline the extraordinary force of the tides that create the whirlpools. Visitors should enjoy the spectacle from designated sightseeing boats and observation facilities rather than attempting to approach the currents independently.
Naruto Strait has also inspired Japanese popular music. Singer Natsuko Godai released her single “Naruto Kaikyo” on April 21, 1996, and it reportedly sold approximately 400,000 copies. In 2010, a monument commemorating the song was erected at the Uzushio roadside station on Awaji Island.
Another song with the same title was released by singer Michiya Mihashi in December 1969. These musical references reflect the strait’s place in Japanese popular culture, alongside its reputation as a dramatic natural landmark.
Naruto Strait brings together striking coastal scenery, unusual underwater geography, powerful tidal currents, and a remarkable engineering landmark in the Ōnaruto Bridge. Its whirlpools are the main attraction, but the surrounding national park scenery and views across the sea make the area rewarding to explore even beyond the peak moments of tidal activity.
For the best chance of seeing the whirlpools at their most impressive, check the tide timetable before visiting, as their appearance and intensity depend heavily on the tidal cycle.