It is known as the Taam Ja blue hole. It is hidden in a bay on the Yucatan Peninsula, on the border with Belize. It was formally described in 2023. It is also known as the bottomless hole in the Mexican sea. What is clear is that it is the world record.
The “bottomless” abyss exceeds the Dragon Hole of the South China Sea. It hits bottom at 301 meters below sea level. It is so deep that sound, which usually transfers well in water, is not reflected from its bottom. The hole swallows the echoes of high-frequency acoustic waves before they can penetrate more than 274 meters deep.

Connected to the Caribbean
Researchers want to go further and find out how far it goes. It is being studied by a public scientific research center in Mexico, the Colegio de la Frontera Sur (ECOSUR). They took a boat to the middle of the abyss and released a fishing line in December 2023. On the hook was an instrument capable of measuring pressure, temperature and conductivity data of the water. When the 500 meters of cable had been deployed, the device had not yet reached the bottom.
The limestone and gypsum walls of Taam Ja Blue Hole descend at a slight angle rather than parallel. That’s why the device ended up 420 meters below sea level. Meanwhile, the fund itself, ECOSUR researchers write, is “yet to be reached.” The bottomless hole in the Mexican sea continues to reveal itself.
It is possible that underwater robots could take an instrument to greater depths. ECOSUR researchers are eager to try again. His instrument reached 400 meters inside the hole. At that time, real-time data conveyed changes in water conditions. And, suddenly, they converged with those of the Caribbean Sea. This suggests that the hole could have a tunnel connecting it to the open ocean.
Unique ecosystem
Biologists continue to explore blue holes around the world to better understand their biological community. In some cases they have found totally new forms of life.
«Within the depths there could lie a biodiversity to be explored. And form a unique biotope,” ECOSUR researchers write in the article. The study was published in Frontiers in Marine Science.