A mysterious underwater cavern off the Yucatan Peninsula in Mexico is a dark blue hole teaming with life, ocean researchers say.
Researchers from the Colegio de la Frontera Sur, a branch of Mexico's National Council of Science and Technology, have been studying the cave that was originally discovered in 2021. In the ancient Mayan language it is dubbed Taam ja', which means “deep water”.
“Knowledge provided by fishermen coupled with scientific research on karstic formations” promoted the study of the blue hole in tropical estuary Chetumal Bay, said their report, released on Saturday.
The chasm is 274 metres deep and lets in little light due to its narrow opening on the ocean floor. In the cold, dark temperatures, researchers expected only basic life forms to survive but say that nature is thriving in the murky depths.
This is despite a lack of oxygenated water near the bottom of the hole and high salinity. The study said conditions in the hole were “anoxic” — or without oxygen — below 110 metres.
Some scientists believe that studying life in blue holes could provide clues on evolution.
A 2012 study on underwater sinkholes in Lake Huron in the US said that “time, water, and geologic forces have converged … where oxygen-poor and sulphur-rich groundwater support prolific microbial mats resembling life on early Earth”.
Taam ja’ is the second deepest blue hole in the world, the researchers say, after Sansha Yongle off China, which is 300 metres deep.
The holes are underwater sinkholes normally formed when soluble rock corrodes and collapses leaving a depression on the sea floor.
In pictures: The world's most spectacular sinkholes
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Turkmenistan's Gates of Hell is a gas crater that has been burning since a Soviet drilling operation went awry in 1971. Getty Images -
Aerial view of two giant holes in a road caused by the collapse of a drainage system due to heavy rains in Villa Nueva, 15 km south of Guatemala City. AFP -
A huge sinkhole at a junction in Fukuoka, Japan. Workers managed to fill it up in a few days in 2016. Reuters -
The Great Blue Hole in Belize was formed from an eroded limestone cave in the last ice age, and later flooded as the sea level rose. Getty Images -
The Well of Barhout in Yemen is known for its pungent odours. AFP -
A giant sinkhole caused by tropical storm Agatha appeared in Guatemala City in 2010. Reuters -
Two cars fell in a sinkhole in Harbin, China, in 2018. Reuters -
A cliff diver leaps 26 metres down into the Ik Kil cenote in Yucatan, Mexico. Getty Images -
Dean's Blue Hole in the Bahamas is the world's second deepest sinkhole, at 202 metres. Photo: Wikimedia -
The Dead Sea is home to many sinkholes, such as this one that formed in a car park in Israel in 2020. -
Geology Professor Fetullah Arik takes measurements next to a large sinkhole in Karapinar, Turkey. Getty Images -
One of the rare blue holes located in the waters of Al Dhafra region in the Emirate of Abu Dhabi. About 12 metres deep, the underwater sinkhole is home to grouper, jackfish and corals. The perimeter of the Al Dhafra Blue Hole is approximately 300 meters long and 200 meters wide, encompassing a total area of around 45,000 square metres. Photo: Environment Agency - Abu Dhabi (EAD) -
A tennis court-sized depression at a copper mine in Copiapo, Chile. Reuters -
The Sheeheet sinkhole in Oman's Dhofar region near the city of Taqah on July 25, 2025. AFP
