19K views · 167 reactions | The Blue Hole reaches down 30 metres and its contents can only be seen by diving below the surface. | National Geographic UK | Facebook

The Great Blue Hole is a giant sinkhole you can dive in. | Insider Travel

😱 . . . #sinkholes #ocean #surf #tsunami | Cristian

Before we fully commit to a well we run a test hole bit to see things like: Depth to water Flow potential Formation type Etc. Great crew making this happen! #welldrilling | Blue Sage Services, LLC

The Great Blue Hole is a giant marine sinkhole off the coast of Belize. 🇧🇿 It lies near the center of Lighthouse Reef, a small atoll 70 km (43 mi) from the mainland and Belize City, the hole is circular in shape, 318 m (1,043 ft) across and 124 m (407 ft) deep. It was formed during several episodes of quaternary glaciation when sea levels were much lower. Analysis of stalactites found in the Great Blue Hole shows that formation took place 153,000; 66,000; 60,000; and 15,000 years ago. As the o