What is the world's deepest underwater sinkhole?

What is the world’s deepest underwater sinkhole? The correct answer is Taam Ja' Blue Hole.

Taam Ja' Blue Hole lies in Chetumal Bay near the southeastern Yucatán Peninsula in Mexico. Recent echo-sounding measurements indicate a known depth of approximately 420 meters, making it the deepest known blue hole.

The hole’s bottom has not been physically reached, so its full depth may be greater than the current measurement. Researchers have also noted that sonar readings in complex underwater sinkholes can be affected by water-density gradients, irregular walls, and the shape of the cavern.

Dragon Hole in the South China Sea was previously regarded as the deepest known underwater sinkhole, with a measured depth of 300.89 meters. Taam Ja' surpassed it after newer research published measurements in the 2020s.

Dean’s Blue Hole and the Great Blue Hole are both considerably shallower. The answer therefore reflects current geographical knowledge rather than the older Dragon Hole ranking.