Underwater 'lost city' is really just a cool natural phenomenon

Underwater near Zakynthos, a Greek island, are some interesting and seemingly human-made structures. When they were discovered by tourists diving in the region, assumptions were made and word spread quickly that some archeological artifacts, possibly the remains of a long-lost city, had been discovered. These claims spurred a group of researchers into investigating the matter, and what they discovered was different, but no less interesting: these structures are entirely natural.

It's not hard to see why the tourists assumed the structures were man-made — some are nearly perfectly circular with an open hole in the middle, resembling a giant stone donut. As well, some parts of the area — which measures up to 16ft in size — appear to be somewhat paved, lending to the appearance of old columns and maybe a floor.

To see whether the claims were true, a preliminary analysis of the area was performed, but other signs of human involvement — such as pottery — were nowhere to be found. This led to a research team led by University of East Anglia's Julian Andrews, as well as University of Athens' professor Michael Stamatakis, analyzing the actual composition of the "stones."

Their conclusion is that these 'donuts' are just natural geological phenomenon likely resulting from the natural gases found near the sea's floor. The structures are probably close to a "sub-surface fault which has not fully ruptured the surface of the sea bed," Andrews told CNN. The structures resemble stone because they're essentially a type of natural cement, and they're being shaped by passing currents.