The waters off Cape San Antonio

Why this is extraordinary

Northwest of Cape San Antonio, the last of Cuba before the Yucatán Channel opens, a survey working off the Guanahacabibes peninsula reported unusual shapes on the seabed and called them MEGA. Between 600 and 750 metres down, the geological report says, they sit in a submarine depression whose floor slopes at most about 6 percent. Two kinds of rock rise out of the sand. The larger are long geometric crests, with hollows beside them. The smaller are blocks, some cubic, some like slabs, some pyramidal, and the faces are what the report calls relatively polished. A few of those blocks sit on one another. In places the stack looks like a piece of wall.

Side-scan sonar mosaics, underwater video, sediment samples, bathymetric maps, and the charts of western Cuba were the means, and the work was run from a Cuban research ship. After the shapes reached the press, the words in public were a sunken city, a Maya town, and Atlantis. The report records those words. It does not adopt them.

Three readings are set out. The shapes may be natural, blocks that fell and slid and flowed down a wet slope. Landslide amphitheatres south of the Bajo de San Antonio are the landscape that makes this the attractive reading, and the report calls it the most parsimonious. The catch, which the report prints as well, is the slope next door. Other slopes nearby are littered with irregular blocks, neither lined up nor geometric. Odd stone is easy to find. That particular pattern, on those comparison slopes, is not. Ashore, bands of hard Miocene limestone weather out as long ridges that can look planned, and the report offers that as a reminder that a straight crest is not yet a wall.

Or the shapes were built. Stacked blocks with smooth faces are the part that points that way. Or a ridge that began as natural stone was tidied by people later. The report's last word is its own. The records are not good enough, they were not gathered by a method that can decide, and a conclusion now would be premature. The place stays a question until someone returns with the right tools. No return of that kind is in the sources used here, and no archaeological paper has established a city.

Depth is the other half. At the last glacial maximum the sea stood on the order of 120 metres lower than today. A shore at 600 metres is not that shoreline. A city built in open air, then drowned by the ordinary rise of the sea, would lie near the 120-metre line, not half a kilometre further down. To be a town that drowned, this seabed would have had to drop by hundreds of metres after people were cutting stone, or the blocks would have had to be made in the deep. The report does not claim either. A shallow pavement argued over in the Bahamas, the Bimini Road, is another depth and another kind of stone. This room does not borrow it.

In a 2017 interview the same geologist is narrower than the open ending of that report. He calls claims of huge pyramids and of built walls definitely false. He says the seabed rock should not be called granite, and that limestone is the more likely stone. He leaves open how far the slides go toward explaining the long crests. He also describes a grey plate, filmed on a rock and never brought up, as still an enigma until it is recovered. The catch is that an interview is not a second survey. The plate's size was spoken, and it is not a line in the 2002 report, so this room does not print it. Press depths, a granite label treated as a fact, and an age of many thousands of years are not that report, and they are not used.

There is a real sonar target, described by the geologist who assessed it, and there is no city yet. The pin sits out in that water. It is not a corner anyone has measured to the metre.