Tsushima is a long and a narrow island which lies in the Tsushima strait. It is 138 km from the city of Fukuoka, and 49.5 km from Busan, South Korea. Tsushima consists of two main islands. The northern part is called Kamijima, and the southern part is called Shimojima. The entire island extends about 82km north to south, and about 18km east to west. Since the island is closer to Korea than the main island of Japan, the city of Busan can be seen from the western side of Tsushima when the weather is clear. Due to its geographical features, Tsushima has played an important role in corresponding with the Asian continent since ancient times.