Scientists have expressed concern after one of the world's most unusual natural sites has uncovered a "concerning secret".

They then examined the core, which is made up of hundreds of layers of coarse particles that have been transported from the nearby atoll reef ... Great Blue Hole, a marine sinkhole offshore Belize ...

Belize's Great Blue ... It is visible from space and is easily identifiable by its unique circular formation and location within the midst of the greater Belize Barrier Reef.

And can it be reversed? Narrator: The Great Barrier Reef is big. So big, in fact, that you can see it from space. David Wachenfeld: It's important for people to remember that the Great Barrier ...

The Great Barrier Reef Foundation, with UNESCO and other partners, is also assisting Belize in its sustainable tourism development, which will yield long-term benefits for both the reef and the people ...

the Great Barrier Reef is 2,300km long -- roughly the length of Italy -- and is the only living organism that can be seen from space. When Veron, a former Chief Scientist at the Australian ...

Belize is widely regarded as a global leader in conservation, home to vast rainforests, diverse wildlife and the second-largest barrier reef in the world. The country has implemented protected ...

The reef is so large that it's visible from space. It covers an area of approximately 344,400 square kilometers ...