Shimanami Kaido Bikeway runs between Onomichi in Hiroshima prefecture and Imabari in Ehime, allowing cyclists to hop across several islands of the Seto Inland Sea.
This 70km bikeway connects Onomichi with the islands of Mukaishima, Innoshima (for the pirate Suigun Castle), Ikuchijima (for Kosan-ji), Omishima, Hakatajima, and Oshima, ending in Imabari on Shikoku. You're welcome to walk or jog any length of the bridge, but cycling is the best way to go. The route consists of wide dedicated lanes for bikes and pedestrians, typically alongside but separated from the car roadway. Special bike lanes have been created to provide reasonable approaches to each of the modern bridges connecting the islands.
An excellent English language brochure is available at the bike depots and online here . The brochure provides riders with side-trip directions to sights on each island and alternate routes for those who desire more strenuous rides. The brochure also has information on rest stops, bike depot locations, public transport (if you get tired) and other facilities and there are many choices along the way for lunch, snacks, and other stops. If staying overnight in Onomichi, it is recommended that you pick up a brochure from the bike depot the night before your trip.
The Green Hill Hotel is also the location of the ferry connecting Onomichi with Mukaishima, Innoshima, and Ikuchijima/Setoda. Serious bikers intent on completing the route in a day could do so, but the route is best enjoyed over the course of two days or in one day by taking a ferry from Onomichi to Setoda (bypassing the two most rural islands on the route). Ferries leave Onomichi once an hour starting at 7:20 in the morning; the trip to Setoda is 40 minutes. Tickets are available in the ferry terminal behind the Green Hill Hotel.
The main route is generally flat except for reasonable and well-graded approaches to the bridges and one large hill on Oshima Island. The whole route is free of charge for cyclists and pedestrians.
The "recommended" main route distances are
If traveling in the direction of Onomichi to Imabari, Kosan-ji Temple and Hirayama Ikuo Museums on Ikuchijima Island are about 4 km along the main route. On Omishima Island, in order to visit the Omishima Museum and the Oyamazumi Jinja Shrine Treasure Hall you must make a round trip (15 km total) off the recommended main route. If taking two days for the ride, Tatara on Omishima is a good place to spend the night before/after this side trip to Oyamazumi Shrine.
On the way you will see many orange plantations. In the commercial street of Setoda on the island of Ikuchijima, you will find lemon in many forms (cake, salad, bottle of sauce to bring back as a souvenir…).
Reserving an accommodation in the area is more complicated than usual in Japan: the reservation websites in English have a very limited number of offers. Getting help from someone speaking Japanese and able to reserve by Internet, phone or fax will give much more options.