From the surface, Chetumal Bay looks almost placid – just a wide sheet of water with no hint of drama underneath. But below that calm is Taam ja’, a massive underwater sinkhole, or “blue hole,” that’s turned into an unexpected mystery for scientists.

At first, the plan seemed straightforward: map it with sonar, get a depth, move on. Instead, the early readings created a bigger problem – what if Taam ja’ isn’t anywhere near as shallow as those first numbers suggested?

The most recent measurements point to a hole that drops far deeper than expected, and the true bottom may still be out of reach…