The Dragon Hole is the deepest blue hole on Earth
The core idea stands, but key numbers or details have changed.
TaughtThe deepest known underwater sinkhole (a 'blue hole') is the Dragon Hole in the South China Sea, plunging about 300 metres. That is the record you would have found in any recent reference.
NowIn 2024, researchers reported that Taam Ja' Blue Hole in Mexico's Chetumal Bay reaches at least 420 metres deep, more than 100 metres deeper than the Dragon Hole, and that the instrument never touched the bottom, so the true depth is greater still.
What actually happened
A probe lowered on a cable reached 416 and then 423.6 metres below sea level on two 2023 casts, published in 2024, without hitting bottom. Because the cable descended at an angle rather than straight down, the researchers note the real depth may exceed even that.
The honesty here is built into the finding: this is a 'deepest known' record, and 'known' is doing real work; the bottom of Taam Ja' still hasn't been reached, and a deeper hole could always turn up. What changed cleanly is the answer to a specific quiz-night fact: the deepest measured blue hole is no longer the Dragon Hole.
Newsletter
Get new weekly revisions
Sources
Who was taught this
Still standard through 2024, so anyone who finished school between 1950 and 2024 learned the earlier version.