Sarushima

Sarushima. Located within Tokyo Bay off the coast of Yokosuka, it is the only natural island in the bay. Historically significant for its Edo period fortifications and later Imperial Japanese Navy defenses, the island is now a public park known for its historical ruins and natural scenery. Accessible via a short ferry ride from Yokosuka Chuo, it serves as a popular recreational destination.

Geography and location

Sarushima lies approximately 1.5 kilometers south of the Miura Peninsula within the confines of Tokyo Bay. The island is situated directly opposite the Yokosuka Naval District, placing it in a strategically vital position for monitoring maritime traffic entering the bay toward Tokyo and Yokohama. Its terrain is characterized by steep, rocky cliffs composed primarily of tuff and sandstone, with a small central plateau. The island's coastline features several small coves, with the main landing point located on its northern shore facing the Uraga Channel.

History

The island's recorded history begins in the Edo period, when the Tokugawa shogunate recognized its strategic value for coastal defense. Following the arrival of Commodore Matthew C. Perry and his Black Ships in 1853 and 1854, the shogunate accelerated plans to fortify Tokyo Bay. Initial battery emplacements were constructed on Sarushima in the 1850s to guard against potential incursions by foreign naval powers. After the Meiji Restoration, control of the island was transferred to the newly formed Imperial Japanese Navy, which significantly expanded its military infrastructure. The island remained under naval jurisdiction through the Pacific War, after which it was administered by the United States Navy during the Occupation of Japan.

Military fortifications

The island is renowned for its extensive and well-preserved military ruins, which represent over a century of fortification. The most prominent features are the Meiji period brick fortifications, including underground ammunition storage vaults, observation posts, and gun emplacements designed for coastal artillery. These structures were built with materials such as red brick imported from Fukagawa and are considered important examples of early modern Japanese military architecture. Later additions during the Taishō and early Shōwa period include concrete command centers and barracks. The fortifications were intended to work in concert with other bay defenses like those on the mainland and at Tatsumi Battery to create a crossfire zone across the Uraga Channel.

Natural environment

Despite its military past, Sarushima supports a diverse natural environment. The island is covered with secondary broadleaf forests consisting of species like Japanese evergreen oak and camphor tree, which have recolonized the island. Its rocky shores and cliffs provide nesting sites for seabirds such as the black-tailed gull and streaked shearwater. The surrounding waters form part of a protected marine area, with tidal pools hosting various intertidal organisms. The island's ecosystem has been studied by researchers from institutions like the University of Tokyo and is managed to balance historical preservation with natural conservation.

Tourism and access

Managed by the City of Yokosuka as Sarushima Natural Park, the island is a major tourist attraction. Visitors arrive via a scheduled ferry service operating from Yokosuka Port near the Verny district. Key attractions include exploring the historical fortification tunnels, walking the perimeter hiking trail, and enjoying panoramic views of Tokyo Bay and the Yokosuka Naval Base. The island has basic facilities such as restrooms, a small museum, and picnic areas. Its proximity to other historical sites like the *Mikasa* Memorial Ship and Sankeien Garden makes it a featured stop on regional cultural itineraries.

Category:Islands of Kanagawa Prefecture Category:Tokyo Bay Category:Parks in Japan Category:Fortifications in Japan