A Detailed Overview and History 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 is a popular tourist spot due to its easy access from central Tokyo. The island has a rich history as a former military fortress, and today, the remnants of that past make it an attractive destination for visitors.

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

1. Overview of Sarushima 

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

It is known for its historical significance as a military fortress, used by the former Japanese army from the Meiji era until 1945. The island still preserves structures such as French-style brick barracks, ammunition storage facilities, and tunnels, evoking a scene reminiscent of the movie Castle in the Sky. These remnants once played a vital role in defending the capital, Tokyo, and are recognized today for their historical importance.

In 1995, Sarushima was developed into "Sarushima Park" by the city of Yokosuka and has become a popular tourist destination. During the summer, visitors can enjoy activities such as swimming and barbecuing, while fishing and hiking are popular year-round. In 2015, the island was designated as a National Historic Site, and in the following year, it was also recognized as part of Japan's cultural heritage.

With its convenient access from central Tokyo, Sarushima is a perfect day-trip destination, offering a mix of historical exploration and natural beauty that attracts many visitors.

2. History of Sarushima 

Sarushima, a natural island in Tokyo Bay, is located off the coast of Yokosuka City in Kanagawa Prefecture. Historically, the island played an important role, particularly as a military fortress.

　1. The Construction of Fortifications in the Late Edo Period (1847)

Sarushima’s role in military defense began in 1847 during the late Edo period. At the time, the Tokugawa shogunate needed to bolster the defense of Tokyo Bay against foreign ships. A battery was constructed on the island to guard against foreign threats and to protect the entrance to Tokyo Bay. The battery was equipped with 15 cannons, providing a strategic defense for the capital.

When Commodore Perry’s fleet anchored off Sarushima in 1853, the island was briefly referred to as "Perry Island," drawing international attention. However, after significant damage caused by the 1855 Ansei Edo Earthquake, the shogunate temporarily abandoned the fortifications on Sarushima.

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

In the Meiji era, Sarushima’s military importance grew further. Between 1877 and 1884, the island was fully developed as a defensive base for Tokyo Bay. The army built new batteries, ammunition depots, barracks, and tunnels. Notably, the brick tunnels and barracks were built using a unique "French-style" construction technique, and they remain popular tourist attractions today.

Sarushima Fortress played a vital role in the defense not only of Yokosuka Harbor but also of the entire Tokyo Bay area. Later in the Meiji period, observation posts and lighting stations were added to strengthen its defense capabilities.。

　3. World War II (1940s)

During World War II, Sarushima was once again used as a fortress by the Imperial Japanese Army. Anti-aircraft batteries, including 8cm and 12.7cm guns, were installed to defend Tokyo Bay. However, these defenses proved ineffective against American B-29 bombers.

After Japan’s surrender in 1945, Sarushima was taken over by the U.S. military. The island gradually lost its military function and was returned to Japan in 1961.

　4. Revival as a Tourist Attraction (1990s–Present)

In 1995, Sarushima was transferred to the management of Yokosuka City, and efforts were made to transform it into a tourist destination. During this time, the island’s military ruins were preserved, hiking trails were established, and a beach was reopened in 1996. In 2015, Sarushima was designated as a National Historic Site, further enhancing its value as a tourist attraction.

Today, Sarushima is a popular destination for visitors to enjoy its blend of historical military remnants and natural beauty. It is part of "Sarushima Park," where visitors can enjoy activities such as barbecuing, fishing, and hiking.

3. Highlights of Sarushima 

Sarushima is a unique uninhabited island that blends nature and history, known as the only natural island in Tokyo Bay. It is particularly famous for its historical military fortifications, remnants of its wartime past scattered throughout the island.

　■ Fortress Ruins

One of the island’s key attractions is the remains of fortifications built by the former Imperial Japanese Army. The entire island was fortified with gun batteries, ammunition depots, and barracks. These remnants played a crucial role in defending the capital from the late 19th century until the end of World War II.

Today, you can still see the brick tunnels and barracks constructed using the French masonry technique, preserved in their original state, allowing visitors to feel the weight of the military history that permeates the island.

　■ Tunnel of Love

The “Tunnel of Love” is one of Sarushima’s iconic landmarks. Located in the center of the island, this moss-covered brick tunnel with its arching ceilings creates a mysterious atmosphere. It has become a popular photo spot, attracting tourists who love to capture its unique charm.

　■ Battery Ruins

Sarushima also features several old gun battery sites, where cannons once stood to defend Tokyo Bay. Although the cannons are no longer present, the circular remnants of the battery emplacements remain, offering a glimpse into the island's military past. A walk through these ruins allows visitors to learn about Sarushima’s history while enjoying the surrounding nature.

　■ Oimonohana Plaza

Oimonohana is Sarushima’s observation deck area, offering spectacular views of the sea. From here, you can see Yokosuka, Yokohama, and even as far as the Boso Peninsula, making it easy to understand the strategic importance of the island’s location. The plaza also features rocky terrain, perfect for exploring the tide pools or taking memorable photos.

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 In Conclusion 

Sarushima is a place that seamlessly blends historical military remnants with abundant nature, offering visitors a unique and captivating experience. The island played a crucial role in Japanese history from the late Edo period to World War II and is now a beloved tourist destination.

Why not take a break from the hustle and bustle of the city and visit Sarushima for a day? You can enjoy an exploration of its rich history while refreshing your mind and body in this peaceful environment.