Bustling Tokyo and timeless Kyoto may be better-known, but Japan’s Seto Inland Sea is one of the country’s great treasures. Running 450 kilometers (280 miles) from east to west, this body of water is vast, yet in places so narrow that its tides produce a type of whirlpool called a vortex. Almost entirely surrounded by land, namely the large islands of Honshu, Kyushu and Shikoku, this sea is typically calm—more like a lake than the open ocean.\n\n
The shores of the sea are lined with major ports; it's crisscrossed by shipping lanes and spanned by soaring bridges. The sea is also home to some 3,000 isles, many with old fishing villages and ancient temples—such as the Miyajima shrine, a UNESCO World Heritage Site with a famous red torii gate. In Japanese folklore, the Inland Sea was believed to be the oldest part of the nation, and its islands are the backdrops for countless legends and myths. The Inland Sea National Park is made up of dozens of noncontiguous enclaves whose terrain ranges from shrubby beaches to pine forests where deer and macaques thrive, and its underwater life includes animals as varied as horseshoe crabs and finless porpoises.