Name: El Ojo
Location: Buenos Aires Province, Argentina
Coordinates: -34.251894705027354, -58.82932152015028
Why it's incredible: The island and the lake it floats in are eerily smooth and round.
El Ojo is a mysterious, uninhabited floating island in Argentina's swampy Paraná Delta. Its name, meaning "the eye," comes from the island's striking resemblance to a perfectly round oculus when seen from above.
Filmmakers drew attention to El Ojo in 2016 after researching material for a documentary in the river delta. The crew, led by Argentinian director Sergio Neuspiller, flew over the island and was struck by its appearance amid the delta's cropped vegetation.
"We found the perfect circle, as seen from the air," Neuspiller told the newspaper El Observador at the time in a translated article. "The water looked black but in reality it was completely transparent water, something that is almost impossible to find in the delta [because the waters are generally muddy], but it had a black earth bottom."
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El Ojo floats in a crystal-clear lake that is just as perfectly circular as the island itself. According to El Observador, the island and the lakeshore have mutually created each other's smooth outlines, thanks to the slow, grinding process of erosion.
The island, which is 387 feet (118 meters) in diameter and made of plant matter, floats on a current that circles the lake, causing the circle to rotate on its axis and grate against the banks. This constant motion means El Ojo has widened the lake and shaved its sides into a perfect disk.
The phenomenon is similar to a process observed in the Presumpscot River near Westbrook, Maine, where a large ice disk has formed several times since 2019 through the action of a circular current beneath the surface.
El Ojo moves in a clockwise direction, according to the Argentinian daily newspaper El Cronista. It remains unclear how and when the island originally broke off from the land, but it first appeared in satellite images almost 20 years ago.
While researching the region, Neuspiller and his crew discovered that local residents knew about El Ojo, but that some people feared the island due to beliefs that an ancient deity lives there. Other theories about the island suggest it attracts unidentified flying objects (UFOs) and harbors a Nazi base, according to El Cronista, but there is no evidence to support these claims.
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