Onaruto Bridge is a spectacular suspension bridge connecting Awaji Island in Hyogo Prefecture with Naruto City in Tokushima Prefecture. Spanning the Naruto Strait, part of the Seto Inland Sea, the bridge stretches 1,629 meters and was completed in 1985. It serves as an important transportation link between Shikoku and the main island of Honshu, improving regional connectivity and supporting economic development and tourism.
Onaruto Bridge crosses the narrowest section of the Naruto Strait. Its central span measures 876 meters, the bridge deck is approximately 25 meters wide, and its main towers rise 144.3 meters above the surrounding landscape. Construction took several years, and the bridge has become a celebrated landmark thanks to its immense scale and dramatic natural setting.
At certain times of the year, including the Awa Odori dance festival season and around earthquake memorial events, the bridge is illuminated at night. The combination of its striking silhouette, the surrounding sea, and the famous Naruto whirlpools makes it one of the region’s most memorable sights.
The bridge was planned as part of Japan’s broader efforts to improve transportation across the Seto Inland Sea during a period of rapid economic growth. Beginning in the 1960s, the Honshu–Shikoku Bridge Project aimed to establish reliable connections between the main island of Honshu and Shikoku.
Onaruto Bridge became one of the key links in this ambitious infrastructure project. Its construction cost approximately 78 billion yen, and the completed bridge represented a major achievement in Japanese civil engineering.
Onaruto Bridge forms part of one of the three major road routes connecting Honshu and Shikoku. Together with the surrounding expressway network, it provides an important transportation corridor between the Kansai region and Shikoku, making travel and freight transportation considerably more convenient.
Because strong winds frequently affect the Naruto Strait, traffic regulations and speed restrictions are sometimes imposed for safety. The usual maximum speed is 70 kilometers per hour, but it may be reduced to 40 kilometers per hour when conditions require it.
Onaruto Bridge is a suspension bridge with a main span of 876 meters. The bridge deck stands approximately 45 meters above the water, allowing vessels to pass beneath it. Its structure was engineered to withstand the powerful tidal currents that flow through the Naruto Strait.
One of its most distinctive attractions is Uzu-no-Michi, a glass-floored observation walkway located beneath the roadway on the Tokushima side. Visitors can look down through glass panels to observe the swirling currents and whirlpools far below, offering a thrilling perspective on this remarkable natural phenomenon.
The Naruto Strait is famous worldwide for its powerful tidal whirlpools, known in Japanese as uzushio. These dramatic formations occur when enormous volumes of seawater move through the narrow strait as the tides rise and fall between the Seto Inland Sea and the Pacific Ocean.
The whirlpools are particularly impressive during spring and autumn, when the tidal range is large. Some can exceed 20 meters in diameter, making them among the largest tidal whirlpools in the world.
Visitors can observe the whirlpools from Onaruto Bridge, from the Uzu-no-Michi walkway, or on sightseeing cruises that approach the turbulent waters. Watching the currents twist and collide provides a striking demonstration of the power of nature.
The bridge’s foundations incorporate a specialized multi-column structural design intended to minimize interference with the natural currents of the Naruto Strait. Engineers had to consider the region’s unusual tidal conditions and the importance of preserving the whirlpools, one of its most valuable natural attractions.
Onaruto Bridge is managed by Honshu-Shikoku Bridge Expressway Company and forms part of the Kobe-Awaji-Naruto Expressway. This route connects the Kansai region, Awaji Island, and Tokushima, creating an essential link for both local communities and travelers.
The lower section of Onaruto Bridge was designed with the possibility of accommodating a future Shikoku Shinkansen high-speed railway in mind. However, the Akashi Kaikyo Bridge, which connects Awaji Island with the mainland near Kobe, was built without a railway track. As a result, a separate railway route would be needed to connect Awaji Island to Honshu by rail.
Ideas for a railway crossing through the Kitan Strait and a railway tunnel beneath the Akashi Strait have also been discussed. However, these proposals have not yet become operational railway links.
In 1980, the railway loading design was revised to accommodate the uncertainty surrounding construction of the Shikoku Shinkansen. The revised plan assumed single-track loading, meaning that if railway services were eventually introduced across the bridge, the section would effectively operate as a single-track route.
The opening of Onaruto Bridge greatly improved access between Shikoku and Honshu. Better road connections have supported regional commerce, encouraged tourism, and made freight transportation more efficient. Businesses throughout the connected regions benefit from easier movement of goods and people.
The bridge has also become a major attraction in its own right. Its impressive architecture and proximity to the Naruto whirlpools draw visitors throughout the year, bringing additional economic benefits to surrounding communities.
The idea of building a bridge across the Naruto Strait had been discussed for many decades. In 1914, a politician from the region submitted a proposal for a bridge to the House of Representatives. At the time, however, Japan did not yet possess the engineering technology required to complete such a project.
In 1953, a crossing in this area was incorporated into Japan’s railway construction legislation. In 1973, a basic construction plan for the Honshu–Shikoku bridges was approved. However, the oil crisis and the government’s policies to restrain overall demand temporarily suspended construction plans.
The Honshu-Shikoku Bridge Authority, established in 1970, was responsible for the construction project. The groundbreaking ceremony took place in 1976, and excavation for the bridge foundations began in December 1977. A safety ceremony for the cable installation work was held in 1981.
After years of engineering and construction, Onaruto Bridge officially opened on June 8, 1985. Since then, it has played a vital role in connecting Honshu and Shikoku and has become one of the most recognizable landmarks of the Naruto Strait.
High-voltage power transmission infrastructure is also associated with the bridge. Before its construction, Shikoku Electric Power operated an overhead transmission line across the strait using transmission towers. These towers were removed as part of the bridge project, and a replacement Naruto-Awaji transmission line was installed by Kansai Electric Power.
This integration of transportation and utility infrastructure illustrates the wider role of the bridge in supporting regional development.
One of the most popular visitor experiences is Uzu-no-Michi, an approximately 450-meter-long walkway extending beneath the roadway from the Tokushima side of the bridge. The route leads to an observation area where visitors can enjoy panoramic views of the Naruto Strait and look down through glass floor panels toward the whirlpools approximately 45 meters below.
The combination of the open sea, powerful currents, and immense bridge structure makes this an unforgettable experience for visitors interested in nature, architecture, and engineering.
Observation areas and nearby facilities provide additional opportunities to appreciate the bridge and learn about the history and natural environment of the Naruto Strait. When the bridge is illuminated for special occasions, its outline stands out beautifully against the night sky and surrounding waters.
Onaruto Bridge is one of Tokushima Prefecture’s most celebrated landmarks. Together with the Naruto whirlpools, it represents the region’s remarkable combination of natural beauty and human engineering.
Beyond its importance as a transportation route, Onaruto Bridge has transformed daily life for residents by making travel between regions faster and more convenient. It has strengthened cultural and economic exchanges between Awaji Island and Tokushima and helped create opportunities for local businesses.
Festivals and regional events around the bridge also bring residents and visitors together. Through tourism, commerce, and improved connectivity, the bridge continues to contribute to the vitality of the surrounding communities.
Onaruto Bridge is expected to remain an essential part of the regional transportation network for many years to come. Local authorities and infrastructure managers continue to maintain the structure while exploring ways to enhance its value as a tourist destination.
Environmental protection and sustainable tourism are also important considerations for the surrounding area. By balancing infrastructure maintenance with the conservation of the Naruto Strait’s unique natural environment, the bridge can continue to serve both residents and visitors in the future.
Onaruto Bridge offers much more than a route across the sea. Its impressive suspension structure, the dramatic Naruto whirlpools, and the panoramic views of the strait combine to create one of Japan’s most memorable coastal experiences.
Whether you admire the bridge from the surrounding viewpoints, walk along Uzu-no-Michi, or take a sightseeing cruise to see the whirlpools up close, a visit to this remarkable landmark provides a fascinating encounter with both Japanese engineering and the extraordinary forces of nature.
10 minutes by cab from Fukura Bus Terminal