Map of the islands of Johnston Atoll, showing rim of coral reef.

In December 2000, most of Palmyra Atoll was bought by The Nature Conservancy for coral reef conservation and research.

File: Atoll forming-Fringing reef. png | As the island and ocean floor subside, coral growth builds a fringing reef, often including a shallow lagoon between the land and the main reef

File: Atoll forming-Barrier reef. png | As the subsidence continues the fringing reef becomes a larger barrier reef farther from the shore with a bigger and deeper lagoon inside

File: Atoll forming-Atoll. png | Ultimately the island sinks below the sea, and the barrier reef becomes an atoll enclosing an open lagoon

In Addu Atoll the westernmost islands are connected by roads over the reef and the total length of the road is 14 km.

File: Atoll forming-Fringing reef. png | As the island and ocean floor subside, coral growth builds a fringing reef, often including a shallow lagoon between the land and the main reef.

File: Atoll forming-Barrier reef. png | As the subsidence continues, the fringing reef becomes a larger barrier reef further from the shore with a bigger and deeper lagoon inside.

File: Atoll forming-Atoll. png | Ultimately, the island sinks below the sea, and the barrier reef becomes an atoll enclosing an open lagoon.

At Rangiroa Atoll in French Polynesia, great hammerheads ( Sphyrna mokarran ) feed opportunistically on grey reef sharks that are exhausted from pursuing mates.

The islands stand on a detached reef of their own with very deep waters ( no sounding ) between this reef and the northern end of the main Atoll.

Faadhippolhu Atoll is a smaller atoll with a well-defined barrier reef to the east, on which the NE monsoon ( iruvai ) breaks with violence.

The Atoll has an oval-shaped lagoon ( vilu ) with a narrow fringing reef on its NW side.

Gahaafaru Atoll also known as Gaafaru Atoll or Gaafarufalhu is a small atoll at the eastern end of a large elliptical reef that has proved disastrous to many vessels with the wrecks of Aracan ( 1873 ), SS Seagull ( 1879 ), Clan Alpine ( 1879 ), Erlangen ( 1894 ), Crusader ( 1905 ) and Lady Cristine ( 1974 ).

* 1867 – The United States takes possession of the, at this point unoccupied, Midway Atoll.

* 1867 – United States claims Midway Atoll, the first territory annexed outside Continental limits.

* 1944 – World War II: The Battle of Eniwetok Atoll begins.

* 1944 – World War II: American forces land on Kwajalein Atoll and other islands in the Japanese-held Marshall Islands.

* 1946 – Operation Crossroads: an atomic bomb is detonated underwater in the lagoon of Bikini Atoll.

* Ailinglaplap Atoll – Christopher J. Loeak ( AKA ), Ruben R. Zackhras ( UDP )

* Ailuk Atoll – Maynard Alfred ( UDP )

* Arno Atoll – Nidel Lorak ( UPP ), Gerald M. Zackios ( UDP )

* Aur Atoll – Norman Matthew ( UPP )

* Ebon Atoll – John M. Silk ( UDP )

* Enewetak Atoll – Jack Ading ( UPP )

* Jaluit Atoll – Rien R. Morris ( UDP ), Speaker Alvin T. Jacklick ( UDP )

* Kwajalein Atoll – Michael Kabua ( AKA ), Tony A. deBrum ( AKA ), Jeban Riklon ( AKA )

* Lae Atoll – Rellong D. Lemari ( AKA )

* Likiep Atoll – Donald F. Capelle ( UDP )

* Majuro Atoll – Wilfred I. Kendall ( UDP ), David Kramer ( IND ), Brenson S. Wase ( UDP ), Vice Speaker Alik J. Alik ( UDP ), ' H. E.

* Maloelap Atoll – Michael Konelios ( UDP )

* Mili Atoll – Kejjo Bien ( UPP )

* Namdrik Atoll – Mattlan Zackhras ( UDP )

* Namu Atoll – Kaiboke Kabua ( AKA )

* Rongelap Atoll – Kenneth Kedi ( IND )

* Ujae Atoll – Frederick H. Muller ( UPP )

* Utirik Atoll – Amenta Matthew ( IND )

* Wotho Atoll – David Kabua ( AKA )

* Wotje Atoll – Litokwa Tomeing ( UPP )

That began to change in 1948 when reports of Bikini Atoll tests were circulated among the Air Force, which made information about the bomb more available to planners and helped to convince them of its strategic capabilities.

Islands in colder, more polar regions evolve towards seamounts or guyots ; warmer, more equatorial islands evolve towards atolls, for example Kure Atoll.

Rats have been eliminated from North Island under this project and more schemes are planned, including at Cosmoledo Atoll and on Conception Island.

The village of Ebadon was much more largely populated before the war and it was where some of the irooj ( chiefs ) of Kwajalein Atoll grew up.

This new government is actively pursuing a more productive and mutually beneficial agreement regarding the Kwajalein Atoll Land Use Agreement with the United States.

Since 1993 the Hawaii Department of Land and Natural Resources and volunteers from the Kure Atoll Conservancy group have helped to restore the atoll to a more natural state.

In 2009 the 20 administrative divisions ( that is, excluding Male ') were grouped under seven provinces, with each province comprising two or more natural atolls ( with the exception of the Medhu-Dhekunu Province made up of solely Huvadhu Atoll ).

One study at Johnston Atoll found that none of the sharks examined had moved more than away from their original capture location over periods of up to a year.

Another study at Rangiroa Atoll in French Polynesia found that, after more than three years, around 40 % of the originally tagged sharks were still present on the same reef where they were first captured.

The difficulty of providing adequate naval and air support of simultaneous operations at Tarawa and the much more distant Nauru, plus lack of sufficient transport to carry the entire division required to take the larger, more heavily defended Nauru, caused Admiral Nimitz to shift the 27th's objective from Nauru to Makin Atoll, in the northeast Gilberts.

* Atoll Reef ( 海洋館 )-A four-storey high aquarium holding more than 2, 000 fish from 250 different species, including the Black Spotted Sting Ray, for which a second generation was successfully bred at Ocean Park.

Some atolls are divided into two administrative divisions or contain half of an atoll ( In case of Thiladhunmathi to Haa Alif, Haa Dhaal, Shaviyani and Noonu Atolls, Huvadhu Atoll to Gaafu Alifu and Gaafu Dhaalu Atolls and In case of half of Ari Atoll to Alifu Dhaalu Atoll ), while other divisions are made up of two or more natural atolls ( In case of Raa, Baa, Kaafu, Alifu Alifu and Vaavu Atolls ).

Chuuk State also includes several more sparsely populated " outer island " groups, including the Mortlock Islands to the southeast, the Hall Islands ( Pafeng ) to the north, Namonuito Atoll to the northwest, and the Pattiw Region to west.