In 1987 a tour dive operator found a mysterous pyramid off the coast of Yonaguni-jima. Yonaguni is an island by Japan.
Not much is known about the underwater structure and the pyramid. Some people are quick to suggest that the remains are proof of Atlantis or perhaps Lemuria. Others suggested that another civilisation entirely is far more likely given the far Eastern location of Yonaguni.
However, as you suspect, plenty of people are certain these ruins cannot be the remains of a civilisation at all. One suggestion is that these are not even ruins at all but natural formations of rock.
In Pure Spirit
What are your theories about the Yonaguni underwater structure? Do you think this is a man-made pyramid or not?