Takenotsuji is the tallest mountain on Iki Island and was formed by pyroclastic basalt from a volcano about 200,000 years ago. From the summit, guests can see all the islands of Iki, and the Watarami Islands of Harushima, Nagashima and Oshima behind them. Guests can also see the shadow of Tsushima Island in the north and the mountains of the Higashi Matsuura peninsula in the south. This area has been used since ancient times for Japan’s defense as a place for signal fires and monitoring the surrounding seas.