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Sarushima of Yokosuka, once a fortress, now an uninhabited island in Tokyo Bay (Kanagawa)

What is Sarushima?

Sarushima is the largest uninhabited island in Tokyo Bay with a natural forest. It is also a popular leisure island, visited by an estimated 150,000 people a year who come to explore on foot the ruins of a former Japanese military fortress hidden in an unspoiled forest. The fortress here was the first modern military facility to be designated as a "National Historic Site" in 2015 and is also a "Japanese Heritage" site. The sunlight shining through the moss and trees is so mysterious that it has been described as "the world of Laputa!" It is sure to be a photo-worthy sight.

Location and Access

Sarushima is an island off the coast of Yokosuka Port in Kanagawa Prefecture. It can be reached by a 15-minute walk from Keihin Kyuko Yokosuka Chuo Station to Mikasa Pier, from which a 10-minute boat ride is available for a day trip.

Origin of the island name "Sarushima(Monkey Island)"

You might think, Sarushima is an island with monkeys, right? In 1253, Nichiren Shonin was on his way across the sea from Boso(Chiba) to Kamakura when he was caught in a storm and lost all track of where he was going. The island is called "Monkey Island" because of the legend that he was guided to the island by a white monkey.

History of Sarushima

Sarushima has a long history, and stone and earthenware artifacts from the Jomon(about 12,000 to 2,500 years ago) and Yayoi(5th century BC~mid 3rd century BC) periods have been found there. 1847, the Edo shogunate built a stone wall on the uninhabited island of Sarushima to protect the Japanese coast from foreign warships, and a cannon platform was constructed there.After the end of World War II, Sarushima became an area forgotten by the public, and as a result, the platforms and fortress-era structures remain today.

Four highlights of Sarushima

  • Cut-through ruins of the fortress

The cut-through was once used by the military, who cut through the mountain to create a 5 to 6 meter-high wall, creating a path so that the military could not be detected from the sky. Along the cut, the actual barracks and ammunition depots that were used remain intact. This place is already part of the fortress! The landscape where heritage and vegetation are blended together creates a world that is truly mysterious.

  • Tunnel of Love

A 90-meter-long, 4-meter-wide, and 4.3-meter-high tunnel made entirely of bricks, it is dark once inside. The tunnel is unlit and dark because the interior is sloped so that enemies cannot see the exit area. It is so dark that couples naturally hold hands with each other, hence the name "tunnel of love. In the photo above, the tunnel of love is on the right, and the left leads to the observatory. This is the most famous photo spot, and is also called "three-way tunnel" because the tunnels intersect on three sides.

  • French brick structure

The barracks and the long tunnel are the only few brick structures in Japan that were built using the "French masonry" method, which is very rare in Japan. They are characterized by their beautiful appearance, with the long and short sides of the bricks stacked alternately.

  • Ruins of a turret

After passing through the fortress, the ruins of a gun turret appear. This is a space where a large cannon can be rotated 360 degrees, and there are the remains of a total of three gun emplacements. It is said that they were aiming at airplanes flying from here.

sightseeing spots around Sarushima

  • Mikasa Park

Mikasa Park, adjacent to the ferry terminal, is a representative park of Yokosuka, selected as one of the "100 Best Urban Parks in Japan" and "100 Best Historical Parks in Japan." The warship Mikasa, on which Commander-in-Chief Heihachiro Togo served during the Russo-Japanese War from 1904, is preserved as a memorial ship. It is the oldest existing steel battleship in the world and is recognized as an important cultural property of Japanese heritage. The interior of the ship is also open to visitors.

  • Tour of Military Ports

For those who wish to see U.S. Navy and Maritime Self-Defense Force ships up close and personal, a 45-minute cruise on the YOKOSUKA Yokosuka Military Port Tour is recommended! Yokosuka Port has developed as a naval port since the black ships of Perry's fleet landed at Uraga in 1853. Since every ship, both Japanese and American, has a mission and is still in operation, the number and types of ships docked are not always the same, so you can enjoy a different view every day. Guides provide thorough explanations, so even if you know nothing at all about ships, no worries!

  • Daini-Kaiho Tour

The Daini Kaibo is located further from Sarushima toward the center of Tokyo Bay. The Daini Kaibo was used as an important defense facility at the entrance to Tokyo Bay during the Meiji, Taisho, and Showa periods, and was closed to the public for a long time, but in 2019, public tours were opened to the public. The central turret, lighthouse, bunkers, and other remnants of the former base can be seen throughout the island.For more details, please watch the video.

As of January 2022, the ban on individual tours has not been lifted, so please take a tour with a travel agency. (If a tour is set up by our company, please click the link at the bottom to view the tour.)

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