A recent post on Reddit’s r/thalassophobia got 7,200 upvotes after showing a crystal-clear lagoon in Brazil that looks almost inviting from the surface. But a flooded cave system lies beneath the bright blue water, and divers have gone more than 220 meters (722 feet) without reaching the bottom.
That is the mystery behind Lagoa Misteriosa, or “Mysterious Lagoon,” in Jardim, in Brazil’s Mato Grosso do Sul state.
The post says Lagoa Misteriosa is a sinkhole that formed after the collapse of a cave ceiling. It sits at the bottom of a doline, which in turn is a depression associated with the dissolution of limestone. According to the attraction’s official site, the cave is several meters below the surface and was formed through the movement of groundwater.
That may help explain why measuring the lagoon is not as simple as dropping a weighted rope into a conventional lake.
The underwater cave system's rock formations and underwater terrain can make exploration difficult as divers descend. Also, the water is exceptionally clear, and visibility exceeds 40 meters (131 feet). That clarity actually creates a visual effect in which, instead of people seeing the water becoming opaque as the water gets deeper, the blue seems to continue into an enormous underwater void.
The deepest recorded exploration of Lagoa Misteriosa was by Brazilian diver Gilberto Menezes de Oliveira in 1998, who reached 220 meters but could not determine the cave’s ultimate depth. So technically, the lagoon is not literally “bottomless,” just that its maximum depth has not been established.
Many commenters moved away from the lagoon's depth and focused instead on jokes about cave diving. Some spoke about the kind of person willing to enter a dark underwater cave; others said that specialized cave diving requires extensive training and equipment. Yet another said that the reason people are drawn to cave diving is the appeal and danger of the environment, which is a combination of darkness, limited visibility, restricted passages, and the fact that they can't be easily rescued.
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Others, however, were more skeptical of the claim that technology cannot explore the lagoon. Most of them said that remotely operated equipment can sometimes be tethered to maintain communication.
No scientific body has publicly stated that modern technology cannot explore the lagoon's full depth, though no such exploration has been documented.
The Daily Dot was unable to independently verify all geological and depth claims cited in this article. Details about Lagoa Misteriosa draw on the attraction's official website and the Reddit thread shared in r/thalassophobia. The details above reflect the post and comments as shared in that community.
