atoll-coral structure in the form of a continuous or broken ring bordering a water basin - a lagoon. The ring of the atoll is formed by separate islands. Some of them have their own lagoon or are an incomplete ring that opens towards the main lagoon with a wide channel. Found only in the tropical zone. They can have different sizes, usually small, but some reach 50 km across. The underwater base of the atoll is usually the heights of the ocean floor of volcanic origin. The genesis of the atoll, according to Charles Darwin's hypothesis, is associated with the slow sinking of a tropical island surrounded by a ring of barrier coral reef, which is gradually expanded by the construction of colonial corals. According to another concept, the formation of atolls occurs as a result of a rise in the level of the World Ocean as a result of the melting of cover glaciers, and not the subsidence of the bottom, as evidenced, in his opinion, by the same depths from which coral structures begin in different atolls. They are very demanding on the complex of natural conditions: the temperature of air and water, the constancy of salinity and dynamics of ocean waters, their purity, etc. They are found mainly in the waters of the Pacific and Indian Oceans.
Plan and vertical section of the atoll (along line AB)
View value Atoll in other dictionaries
Atoll- m. coral island with an open ring; an annular, lagoon ridge, an island, gradually carved out by the smallest skull-dwellers, with a lake or lagoon in the middle (lagoon........
Dahl's Explanatory Dictionary
Atoll- atoll, m. (Malay). Ring-shaped coral island.
Ushakov's Explanatory Dictionary
Atoll M.— 1. A coral island shaped like a ring (sometimes broken).
Explanatory Dictionary by Efremova
Atoll- -A; m. [English] atoll]. A ring-shaped coral island with a shallow lagoon inside (mainly in the Indian and Pacific oceans).
Kuznetsov's Explanatory Dictionary
Atoll- , a ring-shaped CORAL REEF surrounding a shallow LAGOON. The reef appears initially as the frame of an island slowly sinking into the water, usually volcanic........
Scientific and technical encyclopedic dictionary
Atoll- a coral structure in the form of a continuous or broken ring surrounding a shallow lagoon. The base for an atoll is usually the top of an underwater volcano.........
Large encyclopedic dictionary
What is an atoll? An atoll is a ring-shaped coral reef that partially or completely surrounds a lagoon. In other words, an atoll is a narrow piece of land that both borders and is surrounded by water. This is what distinguishes an atoll from an ordinary island. While an island is just a piece of land surrounded by water, an atoll contains a body of water within itself.
Another interesting thing about atolls is the fact that they are not actually made of soil, but of coral. The corals have to grow fast enough to replace parts of the atoll that are being destroyed by erosion in order for the atoll to remain intact. Because corals thrive only in warm waters, atolls can only be found in the tropics and subtropics. Hence, atolls are unique coral land masses consisting of crystal clear lagoon and spectacular colorful reefs overflowing with amazing marine life. Sounds exciting, doesn't it?!
Let's go on an amazing journey through the tropics. From the stunning Aitutaki Atoll in the Cook Islands to the otherworldly beauty of the atolls in the Maldives, we present to you the 25 most stunning atolls in the world.
25. Takapoto, French Polynesia
Takapoto, measuring 20 by 7 kilometers, is an atoll located in the Tuamoto archipelago in French Polynesia. Discovered by Dutch navigator Jacob Le Maire in 1616, the atoll is currently home to approximately 380 people.
24. Aitutaki, Cook Islands
Aitutaki Atoll is home to approximately 2,000 people. It is the second most visited island in the Cook Islands. The atoll, which authorities have protected from mass tourism, is famous for its turquoise waters of the central lagoon and picturesque palm-fringed beaches.
23. Ulithi, Caroline Islands
Ulithi, part of the Federated States of Micronesia, is an atoll made up of 40 islets surrounding one of the largest lagoons in the world. The atoll was the main staging area for the US Navy during World War II. Several sunken ships are still at the bottom of this lagoon.
22. Tubbataha Reef, Philippines
Tubbataha Reef, located in the center of the Sulu Sea, is a marine and bird sanctuary consisting of two large atolls - North and South Atoll. This protected area boasts amazing biodiversity and contains 75 percent of the known coral species and 40 percent of the reef fish species known to science.
21. Tarawa, Kiribati
Tarawa is an atoll and the capital of the Republic of Kiribati, located in the central Pacific Ocean. Home to almost 60,000 people, the atoll boasts a wide reef teeming with fish and a large lagoon spanning more than 500 square kilometers.
20. Tikehau, French Polynesia
Tikehau, located 340 kilometers northeast of Tahiti in the Tuamotu Islands, is an oval-shaped atoll and tourist destination famous for its pink sandy beaches fringed by coconut palms and stunning marine life.
19. Maafushi, Maldives
Maafushi, part of the Kaafu Atoll, is one of the inhabited islands in the Maldives. The atoll was severely damaged by the tsunami in 2004, but quickly recovered. Currently, Maafushi boasts a thriving local economy based on fishing and tourism.
18. St. Francois Atoll, Seychelles
Saint Francois Atoll, consisting of the two islands of Saint Francois and Bijoutier, is an uninhabited atoll in the western Indian Ocean. The atoll is a habitat for numerous species of birds, including the common tern, the curlew, the turnstone, the tule and so on.
17. Rangiroa, French Polynesia
, one of the largest atolls in the world, consists of approximately 415 tiny islands and shoals, covering a total area of about 170 square kilometers. In the center of the atoll, there is a large lagoon where black pearl oysters are bred.
16. Palmyra Atoll, Equatorial North Pacific Ocean
Palmyra Atoll, located between Hawaii and American Samoa, is an unoccupied atoll consisting of an extensive reef, lagoons and 50 islets. The atoll is officially administered by the United States and is covered with coconut palms, scevola and pisonia trees.
15. Nukuoro, Federated States of Micronesia
Surrounding a lagoon 6 kilometers in diameter, Nukuoro is a remote atoll home to almost 400 people. There is no tourism on the island, except for occasional visits from passing sailing yachts.
14. Ontog Java Atoll, Solomon Islands
Ontong Java Atoll is sometimes also called Lord Howe Atoll. It is a large shoe-shaped atoll consisting of more than 120 low-lying islets. There are two large villages on the atoll - Luaniua and Pelau - where most of the atoll's population lives.
13. Nukumanu, Papua New Guinea
Nukumanu is a medium-sized atoll in Papua New Guinea, located in the southwest Pacific Ocean, 4 degrees south of the equator. The atoll consists of 20 sandy islets surrounding a large lagoon.
12. Lihou Reef, Coral Sea Islands Territory
Lihou Reef, located in the Coral Sea, northeast of Queensland, Australia, is the second largest atoll in the world in terms of total area. The atoll, which surrounds a lagoon that extends over an area of more than 2,500 square kilometers, is an important nesting site for many species of birds.
11. Cayo Bolivar, Colombia
Cayo Bolivar, located 25 kilometers from San Andrés, a Colombian coral island in the Caribbean Sea, is an uninhabited atoll consisting of two islands - East Cay and Western Cay. Its diversity of marine life and beautiful beaches have made it a popular destination for tourist excursions.
10. Aldabra, Seychelles
Aldabra, uninhabited and extremely isolated, is a large atoll virtually untouched by man. Known as one of the "crown jewels" of the Indian Ocean, it has a distinctive island fauna, including the largest population of giant tortoises in the world.
9. Ari Atoll, Maldives
Ari Atoll is a natural atoll located in the Maldives. This is one of the largest atolls in the world and is located in the western part of the archipelago. There are more than 20 islands scattered here, most of which have been developed for tourist resorts, and each of them is autonomous and has places for living and recreation.
8. Bangaram Atoll, India
Bangaram Atoll, located in the Union Territory of Lakshadweep, India, is a popular tourist destination offering numerous recreational activities including scuba diving, snorkeling and deep sea fishing. It has white sandy beaches, a calm lagoon and stunning coral reefs.
7. Chagos Islands, British Indian Ocean Territory
The Chagos Islands are a group of seven consisting of more than 60 individual tropical islands in the Indian Ocean. Remarkable for their stunning biodiversity, these reefs are home to at least 371 species of coral, 784 species of fish and 2 species of turtles.
6. Pearl and Hermes Atoll, Hawaii
Pearl and Hermes Atoll, part of the Northwestern Islands of the Hawaiian archipelago, is a small Hawaiian atoll named after two British whaling ships that were wrecked on the atoll in 1822. The atoll was once a center for the pearl trade and is now a bird sanctuary.
5. Osprey Reef, Coral Sea Islands Territory
Osprey Reef, part of the northwestern group of islands in the Coral Sea, is an oval-shaped submerged atoll. The waters surrounding this atoll are 2 kilometers deep and the slopes of its reef are home to a diverse range of marine fauna, including the rare dwarf Nautilus pompilius.
4. Diego Garcia Atoll, British Indian Ocean Territory
Diego Garcia Atoll, located in the central Indian Ocean, just 7 degrees south of the equator, was settled by the French in the 1790s and was later ceded to the British Crown. It has the largest continuous rim of land of any atoll in the world.
3. Kwajalein Atoll, Marshall Islands
Kwajalein, part of the Republic of the Marshall Islands, is one of the largest atolls in the world, judging by the area of water it borders. It consists of 97 islands and islets, and its land area is 16 square kilometers. It surrounds a giant lagoon with an area of 2,174 square kilometers.
2. Kure Atoll, Hawaii
Kure Atoll, politically part of Hawaii, is the northernmost atoll in the world. This atoll is sometimes also called Ocean Island. It provides habitat for hundreds of thousands of seabirds and numerous marine animals, including the monk seal.
1. Ducie Island, Pitcairn Islands
Ducie Island, located in the South Pacific Ocean, is a small uninhabited atoll in the Pitcairn Islands. Despite its sparse vegetation, the atoll is habitat for a number of bird species. More than 90 percent of the world's Typhoon Murphy population nests on Ducie.
The Maldives is a unique creation of nature and an amazing tourist attraction. Located in the Indian Ocean near India, the state is a Muslim republic. At the same time, respect for tourists is so strong that the main Christian holidays are given due attention. The Republic of Maldives consists of several atolls, which in turn include numerous islands. Only 10 groups of atolls out of 20 are open to tourists. Moreover, almost every hotel in the Maldives occupies a separate island, which gives tourists a feeling of peace and serenity. However, there is also something to do for lovers of active recreation - the islands have a lot of opportunities for this, including diving, for which this island state is visited by divers from all over the world. Despite all the exoticism, holidays in the Maldives are distinguished by the highest level of service.
The material on Tourister.ru will talk about the structure of the Maldives - atolls and islands with their description and detailed information. You can also study detailed atoll maps : , , And .
Kaafu Atoll (North Male)
Kaafu Atoll (South Male)
The atoll is divided from North Male by the Vadhoo Strait and extends from west to east for 19 km and from north to south for 36 km. Only three islands of the pearl chain are occupied by local aborigines; the remaining 19 paradise corners have been turned into resorts and delight travelers from all over the world with gentle lagoons and marvelous beaches.
South Male is possible.
Vaavu Atoll
Alternative title: Felidhu
Located 65 km from the capital of the Maldives - Male (90 minutes by speedboat or 5 hours by regular boat). The atoll is an interesting geographical phenomenon, as it consists of two atolls: the main Vavu and a round one, 9 kilometers in diameter, located next to the main atoll. With five inhabited islands and a population of approximately 2,300 people, Vaavu Atoll is the administratively smallest in the Maldives. Besides these five, there are about 14 other islands, but most of them are almost unexplored by tourists compared to the islands of other atolls. Vaavu Atoll is considered one of the best diving spots in the Maldives.
The Fotteyo Candu dive site is considered the best in the country and one of the top five in the world. Vaavu Atoll was opened to tourists in 1975, and has become a favorite among many organizers of various cruises and safaris in the Maldives. The reefs on the eastern side of the atoll are in pristine condition and are perfect for lovers of not only diving, but also snorkeling. There are a lot of sharks here, and there is a chance to see hammerhead fish and other equally interesting fish.
View a detailed map of the atoll and read about tourist islands Vaavu can.
Meemu Atoll
Alternative title: Mulaku
The atoll stretches 50 kilometers from north to south and 30 kilometers in width, housing eight fishing islands and two resort islands. There are excellent places for relaxation and diving here, as confirmed by numerous cruises.
View a detailed map of the atoll and read about tourist islands I guess it's possible.
Seenu Atoll
Alternative title: Addu
The southernmost atoll is located right at the equator, stretching 15 km from north to south and 18 km from west to east. It consists of 5 islands: northern Midu and western Hithadhoo, Gan, Feydhoo and Maradu, united by bridges. There is an airport and a resort hotel on the island of Gan, and the large Hithadhoo ranks second in population after Male - 12,000 inhabitants. Green and pretty Feidu and Maradu rustle with coconut palm plantations; nature has endowed them with small coves where fishing villages have settled. A pleasant surprise awaits hotel guests in Ghana - at any time they will be able to visit the nearby islands and get acquainted with the life of the local aborigines.
View a detailed map of the atoll and read about tourist islands Seen is possible.
Faafu Atoll
Alternative title: Nilandhe North (Nilandhe Atholhu Uthuruburi)
A small atoll, has an oval shape and the second name is North Nilande. It stretches 21 km from west to east and 45 km from north to south, containing five fishing islands and only one resort island, which was recently opened to travelers.
View a detailed map of the atoll and read about tourist islands Faaf is allowed.
Dhaalu Atoll
Alternative title: Nilandhe South (Nilandhe Atholhu Dhekunuburi)
Dhaalu Atoll is located 150 km north of Male and 5 km from Faafu Atoll. It is also known as Nilandhe Atholhu Dhekunuburi (South Niladhe Atoll). It is separated from North Nilade (Faafu Atoll) by the Deburiiterey Kandu Strait. The airport and other atolls can be reached by seaplane or speedboat.
Dhaalu Atoll, 38 km long and 23 km wide, has about 46 islands, many of which are uninhabited. The seaplane transfer takes 40 minutes. Dhaalu Atoll was recently opened for tourism. The islands, open to tourists, are located in the northern part of the atoll and provide excellent diving opportunities. The main island is Kudahuvadhoo Island. This is a fairly large island with developed infrastructure and a population of 1,500 people.
The main reefs, interesting and accessible for diving, are located along the northern and northeastern parts of the islands. There are practically no shallow reefs inside the atoll.
The lagoon, which is relatively clear of coral thickets, allows you to safely go on a tour of the islands by boat. Dhaalu Atoll still preserves the ruins of ancient monasteries and mosques. On the islands where the indigenous population lives, souvenirs are much cheaper than in the capital.
View a detailed map of the atoll and read about tourist islands Dhaal is possible.
Alif Atoll
Alternative title: Ari, also the northern and southern parts are called Alif Alif and Alif Dhaal
The atoll stretches for 33 km from west to east and 96 km from north to south. The atoll is divided into two honors: Alif Alif (northern) and Alif Daal (southern). In the northern part, in addition to the main atoll, there is a small atoll called Radsu, and in the southern part is the capital Mahibadhu. The atoll includes 70 islands, but only 18 of them are inhabited, and 25 have been turned into resorts. Once upon a time, local aborigines lived by catching sharks and turtles, but since sea hunting has been banned, they are busy servicing tourist hotels.
Baa Atoll
Alternative title: Maalhosmadulu Dhekunuburi
It is an administrative division of the Republic of Maldives, together with Horseborough Atoll, and has its capital at Eidafushi. The atoll stretches 32 km from west to east and 42 km from north to south and includes 10 inhabited islands. Local aborigines make a living by fishing, while at the same time mastering more profitable tourism professions. The underwater world is amazingly diverse and surprises with the most interesting dive sites. Marvelous corals, still untouched by divers, as well as dozens of species of fish await ocean treasure hunters!
Lhaviyani Atoll
Alternative title: Miladhunmadulu Uthuruburi
The atoll is 120 km away from the Maldivian capital, and therefore travelers fly to relax by seaplane. The atoll stretches for 35 km from north to south and 37 km from west to east. Food and goods are brought here by dhoni, which takes 8 hours to travel such a considerable distance. Fadiffolu contains 6 fishing and 4 resort islands.
View a detailed map of the atoll and read about tourist islands Lhaviyani is possible.
Every person has heard the word “atoll” at least once in their life. It came to us from Do you want to take a closer look at this concept and find out what an atoll is? Then let's start with a brief description.
We describe the concept
An atoll is called an atoll that looks like a complete or broken ring. Inside it there is a lagoon, that is, a smaller body of water, which is separated from sea or ocean waters by a narrow strip of shore. A more accurate description of what an atoll is is a rise rising from the ocean floor on which a coral superstructure has formed. In shallow waters, corals form reefs and groups of islands, between which there are straits. Thanks to them, the lagoons communicate with the ocean. But if the atoll is formed as a closed ring, then the waters in the lagoon have lower salinity than in the surrounding ocean. They usually form on extinct volcanoes. The meaning of the word "atoll" can be found in any dictionary.
Structure and stages of atoll formation
Charles Darwin was the first to try to explain the stages of atoll formation. Subsequently, his assumptions were confirmed by numerous observations of modern scientists.
At the first stage, a volcano begins to operate on the ocean floor. Volcanic islands rise somewhat above the surface of the ocean. The slopes are gradually overgrown and the volcano itself is slowly sinking. It takes a long period of time before a colony of polyps reaches the surface. Most of today's atolls were formed after the Ice Age. In order for such a formation to take the form of a closed ring, the subsidence of the volcano and the growth of corals must proceed at approximately the same speed, otherwise the ring will be torn.
However, volcanoes may not submerge into the ocean, in which case a volcanic island remains inside the lagoon. This formation is called somewhat aggressively - a nuclear atoll. There can be many islands formed by coral colonies.
Each atoll has 3 components:
- outer reef slope;
- dense reef platform;
- an internal body of water, that is, a lagoon.
The average height rarely exceeds 4 meters above sea level, but the area of such formations can be quite large. Thus, the largest atoll on the planet is considered to be Kwajalein, which is included in the Marshall Islands archipelago. Its area is more than 2300 km². But 92% of this area is lagoon. And about 15 km² remains on the island land.
Reef building material
Have you already understood what an atoll is? What does the building material from which reefs are built look like? belong to the class of invertebrate bottom organisms. Those types of polyps that have a calcareous skeleton participate in reef formation. Most often, reefs consist of madrepore corals and several types of algae that are capable of releasing lime from the surrounding water. The place where coral reefs form is in the shallow waters of tropical seas. Most of them are located in the Indian and Pacific Oceans.
Where does fresh water come from? How does vegetation appear?
Knowing what an atoll is, many are surprised where fresh water and vegetation come from on the coral islands. There are virtually no rivers, streams or other sources of drinking fresh water on the atolls. It comes here only in the form of rain.
The waves, like giant millstones, grind some of the hardened corals and deposit a layer of sand on the surface of the atolls. This mixture contains seeds of various unpretentious plants. Most often, coconuts brought by the ocean germinate. Gradually, the limestone rocks are covered with palm trees and shrubs. There are usually no animals on atolls, but there is a huge variety of insects. And in the surrounding waters there are many species of fish.
In our minds, picturesque atolls with their turquoise lagoons and colorful reefs are closely associated with sea adventures and eventful beach holidays.
For many, these strange formations are the embodiment of the dream of life on a paradise island covered with tall palm trees and tropical flowers. But what are atolls from a geographical point of view? Where are they located and how do they appear on the surface of the oceans?
What does the word "atoll" mean?
Term "atoll" is of Maldivian origin. In the local tribal language the word Dhivehi atholhu means the administrative unit constituting the Maldives archipelago. The concept first came into English in 1625 thanks to Charles Darwin, who was closely involved in studying the structure of atolls and their distribution around the world.
Initially, the term was synonymous with a lagoon island, and later came to mean “an annular band of reef containing a lagoon.”
What is an atoll?
Today, an atoll is understood as a coral island in the form of a solid or broken ring surrounding a small body of water (lagoon). Most often, such islands are located either as an underwater mountain, which was partially washed away and submerged under water. The lagoon in this case is a volcanic crater, and the land is its rim, rising above the water. 
The height of the atoll, as a rule, does not exceed 3–4 meters above sea level. If the island ring is solid, then the water in the lagoon is less salty than in the ocean. If the ring is broken, then straits appear between individual sections of the island, thanks to which salty ocean water enters the lagoon.
What does the atoll consist of?
Structurally, the atoll includes three separate parts - the outer slopes of the island, the islet itself and the lagoon. The rim of the volcano is crowned with a superstructure formed by coral polyps.
In the process of their life activity, these invertebrate creatures form large colonies, which, as they develop and increase in size, create coral reefs. The rate of rifting in atolls is sufficient to compensate for the height of the islands, which gradually decreases as erosion and subsidence of the mountain peak occur.
How are atolls formed?
According to the theory of Charles Darwin, once on the site of atolls there were volcanoes and mountains, which as a result of eruptive and other geological processes sank under water. 
In the case of volcanoes, subsidence could be caused by eruptions, as a result of which the upper part of the peak collapsed under its own weight and formed a caldera. Over time, the volcanic edges were overgrown with coral reefs, forming a ring belt.
If the volcano does not completely sink under water, then a so-called nuclear atoll is formed, in the lagoon of which an island of volcanic origin remains. Due to the decline in sea level, some ring-shaped islands rise above the water and form raised atolls, which are an ordinary island (without a lagoon) with high marginal ridges along the perimeter. This is a fairly rare occurrence, but similar atoll formations can be found in the Tonga archipelago and southern Micronesia.
Where do atolls form?
Reef-forming corals can only exist in the warm waters of oceans and seas, so atolls are formed exclusively in tropical and subtropical latitudes. The northernmost in the world is Kure Atoll, located in the northwestern part of the Hawaiian archipelago. To the south are the Elizabeth and Middleton atoll reefs, extending into the waters of the Coral Sea.
Most of the ring-shaped islands are concentrated in the Pacific and Indian oceans - in the Maldives, Marshall and Caroline Islands, Seychelles, in the Chagos Archipelago and east of Australia. There are several small atoll groups in the Atlantic located east of Nicaragua. 
Kwajalein Atoll in the Marshall Islands, consisting of 92 rings, is recognized as one of the largest in the world. Its total area is more than 2,300 km², of which over 90% is lagoons.
