Saikai National Park is a marine national park located in Nagasaki prefecture of northwest Kyūshū, Japan. It consists of the coastal regions of Matsuura Peninsula, extending northward from the port city of Sasebo and encompasses the Kujukushima, with over 200 islands to the west, Hirado Peninsula further west, and the coastlines of the Gotō Islands to the far west.
The campaign was ultimately successful, and Sakai National Park was established on March 16, 1955, It was the 18th national park to be created in Japan. This park consists of more than 400 islands, large and small, including Hirado, the Kujukushima Islands, and the Gotō Islands. Hirado retains the historic sites of its erstwhile port for foreign trade. The Gotō Islands have interesting inlets and high cliffs as well as rare volcanic formations.