In 2023, researchers confirmed that Taam Ja’, a blue hole in Chetumal Bay off Mexico’s Yucatán Peninsula, is the deepest known blue hole on Earth. Measurements have exceeded 1,372 feet without reaching the bottom. The hole is unusually difficult to spot from the surface, which helped it remain unnoticed for years.

Blue holes are underwater sinkholes that formed when ancient caves collapsed and were later flooded as sea levels rose. They are typically deep, circular, and largely isolated from surrounding ocean currents. Taam Ja’ was first identified in 2021 after local fishers reported its location to scientists.

During a December 2023 expedition, researchers lowered a conductivity, temperature, and depth profiler into the hole. At depths beyond 1,312 feet, the instrument recorded warmer, saltier water consistent with the open Caribbean Sea. Because the bay is separated from open ocean by land, scientists believe subterranean tunnels may connect the blue hole to the sea through the surrounding rock.

The site lies near the Chicxulub crater, the impact site of the asteroid believed to have contributed to the extinction of the dinosaurs 66 million years ago. Researchers speculate that fractures from that impact may have shaped the local cave systems, potentially linking Taam Ja’ to other underwater formations.

During an early expedition, researchers observed water rising from the center of the hole while the surrounding bay remained calm. The cause of this upward flow has not been determined. Divers involved in the exploration described the environment as unusual and difficult to navigate, though no specific hazards were documented.

The blue hole is not accessible to recreational divers, who are limited to depths of about 130 feet. Professional divers rarely exceed 1,000 feet due to extreme water pressure. Scientists expect that future exploration will require remotely operated vehicles capable of reaching greater depths and enduring the conditions inside the hole.

Little is known about the biological content of Taam Ja’. No fish, crustaceans, or other larger organisms have been observed, even in the upper, oxygen-rich layers. The only life detected so far consists of microscopic organisms. If the hole extends deeper, researchers speculate that any organisms living there may be ancient and adapted to extreme conditions. Some scientists compare the environment to other isolated underwater systems where microbial life survives without oxygen or sunlight.

These conditions are of interest to astrobiologists because they resemble environments that may exist on icy moons such as Europa and Enceladus. Learning how life survives in sealed, hostile subterranean systems on Earth could inform the search for life elsewhere in the solar system.

The scientists involved have not yet determined the full shape or depth of the hole. It is possible that side tunnels, unstable walls, or the chemistry of the water could interfere with future measurements. For now, Taam Ja’ holds the record as the deepest known blue hole, though further research may revise current findings.