Kansai floating airport in Japan is slowly sinking
- Kansai International Airport was built on a man-made island
- The airport has been slowly sinking since it was built
- Experts believe parts could be fully submerged by 2056
Published on May 26, 2025 at 5:57 AM (UTC+4)
by Claire Reid
Last updated on May 27, 2025 at 9:18 PM (UTC+4)
Edited by
Alessandro Renesis
Kansai International Airport in Japan was built on a man-made island and has been slowly sinking into the sea for the last three decades.
The airport serves the Osaka and Kyoto region and is the third busiest in Japan, with around 31.9 million passengers traveling through in 2019.
When it opened in 1994, Kansai International Airport garnered plenty of attention from around the country and further afield, due to the fact that it was built on its own man-made island off the Honshu shore.
However, three decades on, the airport has already sunk 38ft (11.5 meters).
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Kansai International Airport, which recently set a record after operating for 30 years and not losing a single piece of luggage, is unlike any other airport out there – and not just because it doesn’t lose the odd suitcase here and there, but because the airport is situated on a purpose-built man-made island
The foundation of the island the airport is built on is made up of layer upon layer of loosely-packed clay on the sea floor.
Engineers working on the project knew that the additional weight from the new island would cause it to sink, so they used millions of sand drains to help compact the sand.
However, even after carrying out this work, the team knew that the airport would continue to sink.
What they didn’t know was how fast it would sink.
Construction began on the man-made island in 1987, and by 1990 it had already sunk 27ft (8.2m), a lot more than the 19ft (5.7m) engineers had predicted.
To help slow the process, the team decided to strengthen and raise the seawall surrounding the airport and fit some hydraulic jacks that can be used to raise the foundation in stages.
The additional work cost an extra $150 million, but it does seem to be working.
When it opened in 1994, the airport was sinking at a rate of around 20 inches (50cm) per year. This dropped to just three inches (7cm) per year by 2008.
However, there’s still a risk that the airport, which cost a staggering $20 billion to build, will eventually be reclaimed by the sea.
Some experts reckon that parts of Kansai International Airport could be completely underwater by 2056.
While the future of the airport may remain unclear, it’s currently gearing up for a bumper year of travel, with almost 40 million passengers expected to pass through the airport for the World Expo in 2025, which is being held in Osaka.
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Claire Reid is a journalist who hails from the UK but is now living in New Zealand. She began her career after graduating with a degree in Journalism from Liverpool John Moore’s University and has more than a decade of experience, writing for both local newspapers and national news sites. Claire covers a wide variety of topics, with a special focus on cars, technology, planes, cryptocurrency, and luxury.
