Researchers Unveil Second Deepest Global Blue Hole in Mexico

Frontiers in Marine Science recently unveiled groundbreaking research on an exceptionally deep blue hole in the Western Caribbean known as the Taam ja’ Blue Hole. This remarkable discovery sheds light on the geomorphometric and physicochemical features of this submerged karst formation in the Chetumal Bay of the Yucatán Peninsula, Mexico. Unlike the well-documented cenotes in the region, the existence of blue holes in this area was previously unknown. In September 2021, a team of researchers conducted an extensive study of the Taam ja’ Blue Hole, revealing a maximum water depth of 274.4 meters below sea level, making it the second deepest known blue hole globally.

Karst formations such as blue holes, submarine caves, and sinkholes are common features in coastal regions worldwide, including the Caribbean Sea and the Yucatán Peninsula. These formations are a result of limestone dissolution and sea-level oscillations during glacial and interglacial periods. The Taam ja’ Blue Hole’s nearly circular shape and steep walls, covered with biofilms, sediments, and limestone ledges, present a unique ecosystem. The mouth of the blue hole, located around 4.5-5.0 meters below sea level, marks a distinct transition in water properties, with significant temperature and salinity gradients.

The hydrographic profiles of the Taam ja’ Blue Hole revealed a stratified water column with distinct layers, including a hypoxic layer, a chemocline, and an anoxic layer. An in-depth analysis of water samples indicated that the composition inside the blue hole corresponds mainly to diluted seawater. Morphometric analyses of the blue hole’s shape, volume, and perimeter highlighted its conical structure and circularity, with a Gravelius coefficient and elongation ratio reflecting its unique geometry.

The research team also explored the morphological and biological features within the blue hole, including biofilms, sediments, and benthic fauna. Observations of mucoid filaments, worms, and barnacles provided insights into the ecological