Touring the island in a rented car (available at each port) will enable you to see a lot within two or three days -- Iki is, after all, only 17 km long and 15 km wide. Cyclists will have to limit themselves to one or two corners of the island, unless they have a week to spare. You'll see more by bike, though, and feel exuberant afterwards.
Iki and neighboring Tsushima, a spectacular mountainous island that deserves an article on its own, are historically interesting mid-points between Japan and Korea. The remains of a makeshift castle built by Toyotomi Hideyoshi to accommodate troops heading for Korean battles still stand near Iki's Katsumoto.
Other sites are where medieval battles with the Mongol invaders took place. Kofun Period burial mounds dating between 500 and 700 A.D. dot the island. An exciting find was made near Ishida as recently as 1996, of the moat and foundations of a Yayoi Period village, believed to be between 1,700 and 2,200 years old. These historical remnants are subtle in scale, but make fascinating stops.
North from Ashiya, a number of sites along the roadway are battlegrounds where Mongol forces devastated Iki in 1274 and 1281 on their way to invade Kyushu, before being wiped out themselves by a typhoon each time.
In Ashibe-chou (jö), a battlefield marker commemorates the Mongol invasions of 1274 and 1281
The island consists of four main towns; Gonoura, Ashibe, Katsumoto, and Ishida. Located on the island are three ports. The island is full of vegetation consisting mainly of rice and tobacco. There is also a hot springs. Sea urchin is a delicacy there, as well as the local shochu.