Exotic Atafu Atoll

I was going through the kids section of NASA's official website, and found amazing things like back-winged X-29, but one picture stood above all, of which I am most curious... Subhan Allah! Just look at this:

It is called Atafu Atoll. NASA describes it as: An atoll is a circle of coral built up around an underwater island made by a volcano. Inside the circle is a body of water called a lagoon. Credit: NASA