The Seto Inland Sea (瀬戸内海 Seto Naikai) is the body of water between the Japan islands of Honshu, Shikoku and Kyushu.
Many of Japan's largest cities border the Inland Sea, and the countless small islands in the Sea are perfect for off-the-beaten-track exploration.
Boats are the natural way to travel around the sea. There are countless services, most running only short distances; check under your destination of interest for details.
After billions of dollars in construction works, the Seto Inland Sea is now crossed by no less than three stupendously huge bridges. From east to west:
The only train connection across the Inland Sea is via the Seto-Ohashi Bridge from Okayama to Takamatsu and onward. Services are fast and frequent, although no Shinkansen service is available.