Researchers have found a blue hole they say is the deepest in the world – and they still haven’t figured out where it reaches the bottom. The formation is the Taam Ja’ Blue Hole in Chetumal Bay, Mexico, and has so far been measured at 1,378 feet deep, or 420 meters below sea level.
Blue holes are huge underwater holes that appear on the sea floor when limestone rock collapses. Some of the most famous blue holes are located in Central America, especially The Great Blue Hole of Belize. Taam Ja’ is near the border of Mexico and Belize, off Mexico’s Tamalcab Island, and near several other blue holes in Chetumal Bay. Measurements of the depth of the hole and how current flows through it were Published this week in Frontiers in Marine Science.
Taam Ja’ usurps the Dragon Hole in the South China Sea (also called the Sansha Yongle Blue Hole) as the deepest known blue hole. Dragon Hole is about 990 feet deep, surpassing the third deepest blue hole, Dean’s Blue Hole, by more than 300 feet. The Taam Ja’ Blue Hole is twice as deep as Dean’s Blue Hole.
In December 2023, the team measured the sinkhole using a CTD profiler (conductivity, temperature and depth), a set of electronic instruments that can characterize various components of the sinkhole. Comparing hydrographic data from the sinkhole with layers of water in other reef lagoons, estuaries and barrier reefs in Central America and the Caribbean led the team to conclude that “potential underground connections” may exist deep within the sinkhole.
The CTD also revealed an increase in the temperature and salinity of the water in the hole, about 400 meters below sea level. The hot water could be related to volcanic or tectonic processes or geothermal activity at depth, the scientists concluded.
The researchers emphasized that the hole could be much deeper than recent measurements, based on the structure of interior limestone cave systems. The team made specific reference to Krubera-Voronya, the deepest known cave, at 2,191 meters deep.
“This highlights the need for continued exploration of these karst geological structures, their intricate geomorphology and the development of branching caves,” the study authors wrote. “Delving deeper into the underwater spatial geomorphology of the TJBH, the focus is on deciphering its maximum depth and the possibilities of it being part of an intricate and potentially interconnected underwater system of caves and tunnels.”
Researchers have not outlined specific plans to remeasure Taam Ja’, but investigation of its depth has only been halted by technological limitations. They highlighted that future investigations of the hole “should incorporate advanced underwater navigation technologies” to better explore the mysterious – and previously unknown – depth of the mysterious hole.
