Formally name the Seto Inland Sea (瀬戸内海, Seto Naikai?), the Inland Sea is the body of water separating Honshū, Shikoku, and Kyūshū, three of the main islands of Japan. It serves as an international waterway, connecting the Pacific Ocean to the Sea of Japan. It connects to Osaka Bay and provides a sea transport link to industrial centers in the Kansai region, including Osaka and Kobe. Before the construction of the Sanyō Main Railroad Line, it was the main transportation link between Kansai and Kyūshū.