A Detailed Guide to the History and Overview of Sarushima

 

　Table of Contents

1. Overview of Sarushima
2. History of Sarushima
3. Highlights of Sarushima
   

Introduction

Sarushima is the only natural uninhabited island in Tokyo Bay and a popular tourist destination easily accessible from central Tokyo. The island has a history of serving as a military fortress, and today it has become a fascinating tourist spot with its historical ruins still intact.

In this article, we will take a deep dive into the historical background and natural beauty of Sarushima, while introducing the must-visit spots on the island.

Overview of Sarushima

Sarushima is the only natural uninhabited island in Tokyo Bay, located approximately 10 minutes by boat from Yokosuka City, Kanagawa Prefecture. The island has a total area of about 56,600 square meters, with a circumference of approximately 1.6 km and an elevation of about 40 meters, making it a relatively small island.

The island is also known as a historic military fortress, having been used as a fortress by the former Japanese military from the Meiji era until 1945. On the island, French-bond brick barracks, ammunition depots, and tunnels still remain, creating an atmosphere reminiscent of the anime film “Castle in the Sky” (Laputa). These ruins played an important role in defending the capital city of Tokyo, and their historical value is still highly regarded today.

In 1995, Sarushima was developed as “Sarushima Park” under the management of Yokosuka City, and has since become a beloved tourist destination for many visitors. During the summer months, visitors can enjoy swimming and barbecuing, while fishing and hiking are popular activities throughout the year. In 2015, the island was designated as a National Historic Site, and the following year it was also certified as a Japan Heritage site.

With easy access from central Tokyo and the ability to enjoy a day trip, Sarushima is visited by many tourists as an ideal place for historical exploration and enjoying nature.

History of Sarushima

Sarushima is a natural island located in Tokyo Bay, belonging to Yokosuka City, Kanagawa Prefecture. This island has played a historically significant role, particularly as a military fortress.

　1. Construction of the Battery (Daiba) at the End of the Edo Period (1847)

Sarushima began its military role in 1847, during the late Edo period. At that time, the Tokugawa Shogunate needed to strengthen the defenses of Tokyo Bay in preparation for the arrival of foreign ships. A battery (daiba) was built on Sarushima to counter the threat of foreign vessels, serving as a crucial defense point to prevent foreign fleets from entering Tokyo Bay. The battery was equipped with 15 cannons and played a strategic role in fortifying the defenses of Edo (present-day Tokyo).

When Commodore Perry’s fleet anchored off Sarushima in 1853, the island was temporarily named “Perry Island,” drawing international attention. Additionally, the Ansei Great Earthquake of 1855 caused significant damage to the battery, leading the Tokugawa Shogunate to temporarily abandon the Sarushima battery.

　2. Fortification During the Meiji Era (Late 19th Century)

During the Meiji era, the military importance of Sarushima grew further. Between 1877 and 1884, Sarushima was developed in earnest as a defense base for Tokyo Bay. The army reinstalled batteries and constructed ammunition depots, barracks, and tunnels. In particular, the French-bond (Flemish-bond) brick tunnels and barracks were built using a distinctive construction technique and are now well-known as tourist attractions that still stand today.

The Sarushima fortress played an important role not only in defending Yokosuka Port but also as part of the overall defense of Tokyo Bay. Furthermore, in the latter half of the Meiji era, observation posts and searchlight stations were added, strengthening its defensive capabilities.

　3. World War II (1940s)

During World War II, Sarushima was once again used as a fortress by the former Japanese military. During this period, anti-aircraft batteries were installed on Sarushima, making it a base for defending Tokyo Bay. Specifically, 8cm high-angle guns and 12.7cm twin-mount high-angle guns were deployed, along with searchlights and other equipment, though they had little effect against American B-29 bombers.

After the war, in 1945, Sarushima was seized by the American military. The island gradually lost its function as a defense fortress and was returned to Japan in 1961.

　4. Revival as a Tourist Destination (1990s Onward)

In 1995, Sarushima was transferred to the management of Yokosuka City, and development as a tourist destination began. During this period, the preservation of fortress ruins and the construction of walking trails were carried out, and the following year in 1996, the swimming beach was reopened. In 2015, Sarushima was designated as a National Historic Site, further enhancing its reputation as a tourist destination.

Today, Sarushima is beloved by many visitors as “Sarushima Park,” where historical military ruins and rich nature harmoniously coexist, offering leisure activities such as barbecuing, fishing, and hiking.

Highlights of Sarushima

Sarushima is a unique uninhabited island where nature and history merge, known as the only natural island in Tokyo Bay. In particular, many historical fortress ruins remain, with spots scattered throughout that evoke the remnants of wartime.

　■ Fortress Ruins

One of the most iconic highlights of Sarushima is the fortress ruins established by the former Japanese military. The entire island was fortified, with batteries, ammunition depots, barracks, and other structures scattered throughout. These played a crucial role in defending the capital from the late 19th century through World War II.

Even today, French-bond brick tunnels and barracks are preserved in their original form, allowing visitors to experience the imposing atmosphere of the military fortress.

　■ Tunnel of Love

The brick tunnel known as the “Tunnel of Love” is one of the famous landmarks of Sarushima. Located in the center of the island, its moss-covered walls and arched ceiling create a unique and mystical atmosphere. This tunnel is also a popular photography spot and a must-visit location for all tourists who come to the island.

　■ Battery Ruins

Sarushima has several battery ruins where the sites of cannons that were once installed here remain. These batteries played an important role in defending Tokyo Bay, but today the cannons themselves are gone, and circular open spaces tell the story of their history. Walking through the battery ruins is a route where you can learn about the history of Sarushima while also enjoying nature.

　■ Oimono-hana Plaza

Oimono-hana is the observation deck area of Sarushima, offering a magnificent view stretching out toward the sea. From here, you can enjoy a panoramic view of Yokosuka, Yokohama, and even the Boso Peninsula, giving you a real sense of Sarushima’s strategic location. The plaza also features rocky shores, making it an ideal spot for tide pool exploration and photography.

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Summary

In conclusion, Sarushima is a captivating place where historic military fortress ruins and rich nature come together. Deeply connected to Japan’s history from the end of the Edo period through World War II, it is now beloved by many visitors as a tourist destination.

Why not escape the hustle and bustle of the city and spend a day on Sarushima, enjoying historical exploration and a refreshing break?