A battleship-shaped Japanese island was more than 17 times as densely populated as Tokyo in 1959; now it’s a ghost town you can’t explore alone

Imagine squeezing more than 5,000 people onto an island just 480 metres long and 150 metres wide. There would be almost no room for open land. Apartment blocks would rise wherever buildings could fit. Schools, shops, restaurants, hospitals and public baths would have to be packed into the remaining spaces. Around them, enormous concrete walls would stand between the residents and the sea.

This was not a futuristic experiment or a temporary refugee camp. It was everyday life on Hashima Island, a tiny piece of land off Nagasaki, Japan, better known as Gunkanjima, or “Battleship Island.”

At the height of its coal-mining boom, roughly 5,300 people lived on the island. And then, in 1974, it happened almost as quickly as it sounds impossible: the mine closed, the residents left, and an entire community disappeared.


Today, Hashima is a haunting landscape of abandoned apartment blocks, schools, and industrial ruins surrounded by the sea. The island that once represented Japan's rapid industrial rise has become one of the country's most striking symbols of industrial decline.

Comparison with Tokyo

At its peak, Hashima Island was extraordinarily crowded even by the standards of modern megacities. Around 5,259 people lived on just 6.3 hectares in 1959, producing an overall population density of roughly 83,600 people per square kilometer, as per a CNN report from 2013. By comparison, Tokyo Prefecture had a population density of 6,365 people per square kilometer in 2025. That means Hashima's historical density was dramatically higher; Nagasaki's tourism authority describes it as 17.5 times the density of Tokyo and says it was regarded as the world's most densely populated place.

How could thousands of people live on such a tiny island?

During its peak years, thousands of people lived there alongside the enormous infrastructure required to operate an undersea coal mine.

The island's population density was extraordinary because there was almost nowhere to expand. Instead, Hashima grew upward and outward. Large reinforced-concrete apartment buildings were constructed close together, while sea walls were built around the island to protect it from powerful waves and typhoons.

The result was an urban landscape compressed into an area that would feel tiny even by city standards.

The comparison with Tokyo makes the scale easier to imagine. Tokyo is famously crowded, but its population is spread across a vast metropolitan area. Hashima concentrated thousands of residents onto a few hectares of land. People did not simply live close together; almost every part of the island had a purpose.


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Half of Hashima was devoted to the mine and its associated facilities. The rest was transformed into a tightly packed residential and community area. There were schools for children, shops, restaurants, a hospital, a public bath, and other facilities needed to support a permanent population.

From coal discovery to an industrial powerhouse

Coal was reportedly discovered on Hashima in 1810 by the feudal lord of Saga. Industrial-scale mining began later in the 19th century, when Japan was rapidly modernizing and coal became an essential source of energy. Mitsubishi eventually purchased the island and expanded the mining operation.

As coal production grew, so did the population. Workers arrived with their families, and the tiny island gradually became a self-contained industrial community.

The mine extended beneath the sea, while the surface became increasingly crowded with housing and infrastructure. The island's distinctive silhouette, with its high-rise concrete buildings and surrounding seawalls, eventually earned it the nickname Gunkanjima, meaning “Battleship Island,” because its outline resembled a military battleship. At its peak, around 5,300 people were living there.

The island had become an extraordinary example of how far industrial society could reshape a landscape.

Then the coal industry changed and Hashima emptied

Hashima's extraordinary rise was ultimately tied to the same force that caused its collapse.

Japan's energy needs were changing. Coal was replaced by other sources of energy, particularly petroleum. In April 1974, the Hashima mine closed.

There was no gradual transformation into another industry. The reason for living on the island had largely disappeared.

Residents left, taking their belongings and their everyday lives with them. Buildings that had once been filled with families suddenly stood empty.

Within a short period, Hashima went from one of the most densely populated places imaginable to an abandoned island.

Nature began reclaiming the island

With no residents maintaining the buildings, Hashima was left exposed to the sea and weather.

Typhoons battered the concrete structures. Saltwater accelerated deterioration. Windows broke, walls weakened, and vegetation began appearing among the ruins.

The apartment blocks, schools, and mining facilities slowly transformed into a landscape of crumbling concrete.

For years, the island was effectively off limits because of the danger posed by unstable structures. Visitors could see it from boats circling the island, but they could not simply step ashore and explore.

That isolation helped create the eerie reputation Hashima has today.

The buildings are not ancient ruins. They are remnants of a modern industrial community that disappeared within living memory.

Hashima finally reopened to visitors

A new boat dock was completed in 2009, allowing organized sightseeing tours to land on the island.

Visitors are restricted to designated areas and observation decks because much of the island remains structurally unstable. Tours typically spend only a limited amount of time on Hashima, with guides explaining its mining history and the lives of its former residents.

Visitors cannot explore the island independently. Access is controlled through tour groups, and tours can be canceled because of severe weather.

The journey from Nagasaki takes roughly 50 minutes by boat and provides views of the city's coastline, nearby islands, and Mitsubishi's shipbuilding facilities.

The voyage itself offers an important contrast: modern Nagasaki continues to function as a living city while Hashima sits offshore as a frozen remnant of another industrial era.