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The Mystery of the Yonaguni Undersea Ruins

2025.11.24
Photo Credit: Melkov/Wikipedia

Have you ever heard of the Yonaguni Undersea Ruins? They are one of Japan’s mysteries. Many people in Japan have never heard of them, but divers around the world know this strange and beautiful place. The ruins are under the sea, near Yonaguni Island in Okinawa.

In 1986, a local diver discovered something surprising while swimming near the island. He saw huge stone shapes on the sea floor. The shapes looked like steps, walls, and even roads. Everything looked very straight and sharp, almost like they were cut by people. The diver thought he had found an ancient city under the sea.

But here is the mystery: no one knows if the ruins are natural or human-made.

Some scientists say the Yonaguni ruins were made by nature. They believe the rocks slowly broke into shapes over thousands of years. Strong waves, earthquakes, and wind may have created straight lines in the rock. According to these scientists, the ruins are beautiful, but not made by humans.

Other researchers say the ruins look too perfect to be natural. The steps are very even. The walls look straight. Some stones look like they were placed carefully. There is also a wide, flat “plaza” that looks like a meeting place.

Some people believe Yonaguni was once part of a very old civilization from more than 10,000 years ago, before the sea level rose. If this is true, the ruins could be one of the oldest human structures in the world.

The ruins are deep underwater, so it is difficult to study them. Divers can only stay down for a short time. Also, there are no clear signs of tools, pottery, or human bones. Without these, it is hard to prove that people built the ruins.

Because there is not enough evidence, the mystery continues. Are the shapes natural rock formations? Or did people build them long ago?

Today, many divers visit Yonaguni Island to see the ruins with their own eyes. The water is clear and blue. Hammerhead sharks even swim nearby in winter. Whether the ruins are natural or human-made, they are one of Japan’s most interesting and mysterious places.

If you visit Okinawa, you can see the ruins yourself and decide what you think they really are.


Useful Vocabulary

ruins – old buildings that are broken or destroyed
civilization – a large, organized society in history
plaza – a flat open space
formation – the shape something has
evidence – information that shows something is true


Comprehension Questions

A. Multiple Choice

  1. Where are the Yonaguni ruins located?
    a) Near Tokyo
    b) Under the sea in Okinawa
    c) In South America

  2. When were the ruins discovered?
    a) 1986
    b) 1960
    c) 2010

  3. What do some scientists believe?
    a) The ruins were made by aliens
    b) The ruins are natural rock formations
    c) The ruins are a modern building

  4. Why is it difficult to study the ruins?
    a) They are too dangerous to touch
    b) They are underwater
    c) They are in a desert


Scroll down for the answers









Answers


  1. b) Under the sea in Okinawa

  2. a) 1986

  3. b) The ruins are natural rock formations

  4. b) They are underwater

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