This is a really bizare story, which I've been fascinated by since hearing about it in the summer.
In 2006, a small group of Italian cave explorers claimed to have explored a quartzite cave in the province of Amazonas to a depth of 670m. This made it not only the deepest cave in Brazil, but in the entirety of South America, and also the deepest quartzite cave in the world.
Understandably, the Brazilan cavers were very interested in this cave and in 2015 staged a Brazilan-Italian expedition to the cave to properly document and survey the cave given the lack of data produced by the original explorers.
The cave was located exactly according to the co-ordinates, and photos of cave matched those published. To their surprise though, rather than continuing to -670m, the cave firmly choked off at a depth of 107m, and all efforts at finding a downward continuation failed. There was no evidence of a collapse blocking the way on, and the survey published in 2006 did not match the cave explored in 2015.
The conclusion then is that the original explorers simply fabricated the other 560m of depth. While fairly shocking to the 2015 team, this made sense given numerous oddities, contradictions, and inconsistencies they’d noticed in the account of the 2006 exploration. Before and after 2015 expedition the original Italian explorers extremely evasive and difficult to get a hold of, and provided very little information to the Brazilian team. Now, the 481m deep Gruta do Centenário is considered the deepest cave in Brazil.
You can watch a short video (w/ english subtitles) on the expedition here;
And also a longer talk in Portuguese here, which really fleshes out the story. I don’t think the automatic subtitles in english are much use though…
Here's the Italian team's account of the cave exploration in 2006;https://www.akakor.com/spedizioni/2006-2010/amazzonia-2006/
Does anyone else know of stories of caving fraud like this? I for one can’t think of a case of someone inventing a discovery, of any size, and passing it off as actual cave passage. Especially not on this grand scale.