What is a blue hole

Blue holes are massive underwater karst pits that appear on the seafloor when limestone rocks break up. Some of the most famous blue holes are located off the coast of Central America, most notably the Great Blue Hole in Belize. Taam Ja is located near the Mexico-Belize border, off the coast of the Mexican island of Tamalcab and near several other blue holes in Chetumal Bay.

Measurements of the depth of the hole and how the current moves through it were released this week. Depth defined so far 420 meters. But researchers haven’t reached the bottom yet.

Taam Ja tops the Dragon Hole (also known as the Sansha Yongle Blue Hole) in the South China Sea as the deepest blue hole known to date. The depth of the “Dragon Hole” is approximately 275 meters, which exceeds the third deepest blue hole, the Dean Blue Hole, by more than 90 meters. The Taam Ja Blue Hole is more than twice as deep as the Din Blue Hole.

See what the entrance to the Taam Jah blue hole looks like: video

In December 2023, the team measured the sinkhole using a CTD (conductivity, temperature, and depth) profilometer, a set of electronic instruments that can characterize various components of the sinkhole. Comparing sinkhole hydrographic data with layers of water in other reef lagoons, estuaries, and barrier reefs in Central America and the Caribbean led the team to conclude: there may be “potential underground connections” deep in the funnel.

Dredging of the blue hole Tham Ja in 2023. At that time, only a depth of 275 meters was confirmed / Photo: Alcérreca-Huerta et al., Front. March. Science.

Researchers emphasized that the hole could be much deeper, than recent measurements based on the structure of internal limestone cave systems. For example, scientists know of a cave with a depth of 2,191 meters.

Measurements are currently suspended due to technological limitations. The researchers did not indicate plans to continue measuring Taam Ja.