World's deepest under-ocean sinkhole found by researchers

World's deepest under-ocean sinkhole found by researchers

Researchers have discovered the deepest sinkhole known on Earth, located underwater near the border of Mexico and Belize. Previously believed to be the second-deepest of its kind, the Taam Ja’ Blue Hole (TJBH) is now recognized as the deepest known blue hole, with its bottom still uncharted. A recent paper published in the journal Frontiers in Marine Science suggests that the TJBH plunges to at least 420 metres below sea level.

Named ‘Taam Ja’’ in Yucatec Maya, which translates to ‘deep water’, the blue hole has proven to be a challenging depth to measure precisely for the research team. Scientists have been studying coastal karst formations in Chetumal Bay, Mexico, south-east of the Yucatan Peninsula, focusing on these remarkable structures known as blue holes. One of these, the TJBH, was initially measured at approximately 274 metres deep using echosounder mapping, establishing it as the second-deepest blue hole in the world at the time. However, the use of echosounders in complex environments such as blue holes presents challenges due to factors such as varying water density and cave shapes. Initial attempts to explore the TJBH’s depth did not reach the bottom, necessitating further investigation.

Further exploring the blue hole

Recent measurements employing a CTD (conductivity, temperature, depth) profiler found depths exceeding 420 metres, confirming TJBH as the world’s deepest known blue hole. The research also revealed different layers of water within the TJBH, indicating connections to other water bodies such as the Mesoamerican Barrier Reef System.

As described in the Frontiers in Marine Science paper by Alcérreca-Huerta et al. (2023), new CTD profiles were conducted within the TJBH. Using a SWiFT CTD profiler from Valeport, a UK-based manufacturer of oceanographic instrumentation, single profiles were taken at each campaign with simultaneous measurements of water pressure, temperature and conductivity throughout the water column. Featuring survey-grade sensor technology, the SWiFT CTD profiler offers the convenience of Bluetooth wireless technology, a rechargeable battery and an integrated GNSS module for accurate profile geolocation. The coordinates for the CTD profiles were 378830.7m E and 2059383.6m N (UTM 16Q), based on preliminary echosounding measurements indicating water depths exceeding 250 metres below sea level. The vessel was anchored to prevent drifting caused by waves and currents. In this specific location, the CTD instrument was lowered, utilizing approximately 500 metres of cable down to the bottom, adhering to the maximum depth supported by the instrument.

The research team now plans to further explore the TJBH using robots and unmanned submarines to map its depths accurately. Advanced underwater navigation technologies will be used in conjunction with CTD profilers to provide a detailed three-dimensional spatial representation of the TJBH and its geomorphological features and water depths.

The Taam-ja’ Blue Hole (TJBH) surpasses the depths of famous blue holes like the Sansha Yongle Blue Hole in the South China Sea, Dean’s Blue Hole in the Bahamas, and the Dahab Blue Hole in Egypt. It even outstrips the iconic Great Blue Hole in Belize, as pictured here. (Image courtesy: Shutterstock)
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