Apataki

I got just one pic, taken from the Pacific, of this first atoll (following the alphabetical order). You can easily notice the shape and the weakness of the atoll.

The two land borders (in the centre of the picture) are the edges of the ring which costitute this atoll. In the foreground there's the Pacific and the lagoon (which is the turquoise one).

If you arrive from the ocean you'll see the perimeter of the atoll, that is its first defense against the violence of the ocean.