Belize

Every day, waterfalls of sand fall into The Great Blue Hole in Belize, slowly filling it up like an underwater hourglass. 

The Great Blue Hole is one of the largest underwater sinkholes in the world. From the air it looks like a giant poked a finger in the sea-bottom leaving a circular deep blue hole. Vertical walls plunging down from a sandy sea bottom.

Scuba divers and snorkelers have been cruising the surface waters for decades, but not until recently have a deep sea team discovered what lies deeper. And by doing so reveal history. The hole was once a deep dry cave. Findings also show evidence of huge storm cycles followed by significant droughts around the time of the Mayan collapse. 

Don’t be too alarmed by sand slowly filling it up if you want to explore it. The sands of time will need thousands of years to get there.