Geography of Japan
Japan is an island nation comprising a stratovolcanic archipelago over along East Asia's Pacific coast. It consists of 6,852 islands. The main islands are Honshu, Kyushu, Shikoku and Hokkaido. The Ryukyu Islands and Nanpō Islands are south of the main islands. The territory extends . It is the largest island country in East Asia and fourth largest island country in the world. Japan has the sixth longest coastline and the eight largest Exclusive Economic Zone of in the world.
Naval history of Japan
Japan seems to have been connected to the Asian landmass during the last Ice Age until around 20,000 BCE, both because of glaciation of sea water and the concomitant lowering of sea level by about 80 to 100 meters. This allowed for the transmission of fauna and flora, including the establishment of the Jōmon culture. After that period however, Japan became an isolated island territory, depending entirely on sporadic naval activity for its interactions with the mainland. The shortest seapath to the mainland (besides the inhospitable northern path from Hokkaidō to Sakhalin) then involved two stretches of open water about 50 kilometers wide, between the Korean peninsula and the island of Tsushima, and then from Tsushima to the major island of Kyūshū.