World's deepest blue hole discovered in Mexico during scuba diving expedition

Researchers have discovered the world’s deepest blue hole in Mexico, but the catch is they haven’t reached its bottom yet. The site named Taam Ja’ Blue Hole (TJBH) is now the deepest known underwater sinkhole in the world. The measurements show TJBH extends at least 1,380 feet (420 metres) below sea level.

The newly found deepest blue hole, situated in Chetumal Bay off the southeast coast of the Yucatan Peninsula, is 480 feet deeper than what scientists documented in 2021.

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In 2021, the first blue hole was discovered, which was found to be 390 feet (119 m) deeper than the previous record holder- the 990-foot-deep (301 m) Sansha Yongle Blue Hole, also known as Dragon Hole in the South China Sea.

World’s deepest blue hole discovered in Mexico

TJBH was identified as the world’s deepest blue hole during a scuba diving expedition that took place on 6 December 2023. The expedition was conducted to analyse the environmental conditions prevailing at the site, as per the study published Monday in the Frontiers in Marine Science journal.

During the expedition, the researchers took measurements with a conductivity, temperature and depth (CTD) profiler- a device with a set of probes that read and transmit water properties to the surface in real time via a cable.

The data from the device revealed that Taam Ja’ Blue Hole is indeed the “world’s deepest known blue hole, with its bottom still not reached”, the researchers wrote in the study.

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The profiler also highlighted different layers of water within the blue hole, including a layer below 1,312 feet (400 m) where the temperature and salinity conditions resembled those of the Caribbean Sea and nearby coastal reef lagoons. This suggests the TJBH may be connected to the ocean via a hidden network of tunnels and caves, according to the study.

Initial measurements of the TJBH were taken with an echo sounder- another instrument that sends sound waves down to the bottom of the water and measures the speed they come back to calculate distance. However, the instrument had its limitations when it came to measuring deep blue holes.

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The CTD instrument used for the recent work did not find the bottom of the blue hole either, as it could only operate down to depths of 1,640 feet (500 m). Scientists lowered the profiler down to that depth, but the cable it was attached to may have drifted on underwater currents or bumped into a ledge that stopped the device in its tracks 1,380 feet down, according to the study.

Next, the scientists plan to “decipher TJBH's "maximum depth and the possibilities of forming part of an underwater intricate and potentially interconnected system of caves and tunnels," the researchers wrote.

What is a blue hole?

Blue holes are water-filled vertical caverns, or sinkholes, found in coastal regions where the bedrock is made of soluble material, such as limestone, marble or gypsum. They are formed when water on the surface percolates through the rock, dissolving minerals and widening cracks, which eventually causes the rock to collapse.

Some famous examples include Dean's Blue Hole in the Bahamas, the Dahab Blue Hole in Egypt and the Great Blue Hole in Belize.

(With inputs from agencies)