Mexico
Researchers found the planet's deepest under-ocean sinkhole - and it's so big, they can't get to the bottom
Blue holes are considered an "oasis" for marine life – but the Taam Ja' Blue Hole off the coast of Mexico remains largely mysterious.
A dive to the deepest parts of all five oceans
Sinkholes don't just happen on land, they also happen in the ocean where they're known as blue holes. And now, researchers say they've found the deepest one yet on the planet – one so large that they can... [2521 chars]