Hop between small islands by ferry
From Takamatsu, a port city on the island of Shikoku about an hour by train from Okayama, ferries cross the calm Seto Inland Sea to islands large and small in 20 to 60 minutes. Spend the day walking fishing villages and quiet shores. Boats may be cancelled in rough weather, so check the timetable and the day's sailings before you set out.
An island 20 minutes by ferry from Takamatsu, also called Onigashima, or Ogre Island, from the folk tale of Momotaro, the peach boy who sailed out to defeat a band of ogres. A bus runs from the port up to a large cave in the hills said to have been the ogres' hideout. Afterwards, walk the beach by the port while you wait for the boat back.
A small island about 40 minutes by ferry from Takamatsu, where houses are packed onto a steep hillside above the harbor and narrow stone-stepped lanes wind between their stone walls. Climb up through the village, then walk on to the lighthouse of bare granite at the island's northern tip. The lanes are too narrow for cars, so wear comfortable shoes.
A large island about an hour from Takamatsu by car ferry, or about 35 minutes by fast boat. It is big enough that you pick a few places for the day: olive groves above the sea, old soy sauce breweries with huge wooden barrels, and a rocky gorge with a ropeway. Island buses do not run often, so plan your route before you go.