(NewsNation) — Researchers have discovered a blue hole off the coast of Mexico that they believe is the deepest underwater sinkhole in the world, and they’ve yet to reach the bottom of it.

The Taam Ja’ Blue Hole was first discovered in 2021 and was originally believed to be around 900 feet deep; however, a new study published in the journal Frontiers in Marine Science found it’s at least 1,380 feet below sea level.

This makes it 393 feet deeper than the Sansha Yongle Blue Hole, or Dragon Hole, in the South China Sea, which is 987 feet deep and the previous record-holding blue hole.

In December, researchers conducted a scuba diving expedition of the Taam Ja’Blue Hole, which is located in Chetumal Bay off the southeast coast of the Yucatán Peninsula, using a conductivity, temperature and depth (CTD) profiler, and discovered it was much larger than first thought.

The Taam Ja’Blue Hole “surpassed 420 mbsl (meters below sea level) with no bottom yet reached, establishing the TJBH as the deepest-known blue hole globally,” researchers wrote in the study.

Confirmation of the maximum depth wasn’t initially possible due to instrumental limitations during the scientific expeditions in 2021, the study said.

Researchers also noted the salinity of the water in the blue hole resembles that of the Caribbean Sea, which suggests the blue hole may be connected to that ocean via hidden tunnels.

Researchers hope to conduct further investigations of the depth and properties of the Taam Ja’ Blue Hole.

“Within the depths of TJBH could also lie a biodiversity to be explored and linked to physicochemical and geomorphological processes,” researchers said.