Between the island of Shikoku and Honshu, the main island of Japan, lies the Seto Inland Sea. A chain of islands, large and small, straddles this body of water between Imabari in Ehime, and Onomichi in Hiroshima. The islands are linked by the Shimanami Kaido, a highway with spectacular suspension bridges over the sea passages. The border between the prefectures of Ehime and Hiroshima lies right in the middle. From the Ehime side, the islands of any significant size are Oshima, Hakatajima, and Omishima. Crossing the border into Hiroshima, the road passes over Ikuchijima, Innoshima, and Mukaishima.
The highway is part of Japan’s expressway system, and tolls are levied for vehicles of all types. Unlike most expressways, the Shimanami Kaido has a lane for pedestrians and cyclists, although these are restricted to the bridge sections of the highway. Where the highway crosses an island, the pedestrian lane peels off and descends a looping ramp while the expressway plows on in a somewhat straight line, plunging into tunnels here and there through mountains.
The ability to cross this spectacularly beautiful island route on a bicycle offers an amazing bonanza for cyclists of every sort, from casual day-trippers, to serious riders who long to eat up the miles. It’s also very attractive for motorists and motorcyclists too of course, but going by bicycle allows you to stop and gaze at the scenery whenever you please, and to peer over the railings at the sea and ships below. The sea has a different complexion depending on the time of day, and the low light of early morning and late afternoon creates particularly vivid contrasts.
Currents are strong in the sea due to the large tidal range, complex topography, and the narrow channels and straits. When the tide changes, the surface of the water is dimpled with whirlpools and split by seams of roiled water due to the different heights of the seafloor. From a distance, the sea looks beautifully calm. From directly above, it’s positively frightening.
Whichever means of transport you choose for embarking on your journey across the Shimanami Kaido, it’s best to plan on dedicating some time to the route itself for exploring the islands. There are things to see and do at all times of year, and the islands with their convoluted coastlines are ideal for photographers and birdwatchers. The islands are also renowned for their cherry blossom which pinken the hillsides in early April. On the Ehime side, both Imabari and Matsuyama can be accessed easily by car or train, and by bicycle for those who are used to covering reasonably long distances.
If you explore Shimanami Kaido by bicycle, take protection against the sun, wind, heat and cold, and make sure you get plenty to drink, whatever the season. There are vending machines on all the islands, but not on the bridges.