Last Updated on July 19, 2023 by Editor G
Atolls are formed when coral reefs create a circle that can either partially or enclose a lagoon. They can be found in many of the oceans in the world and are commonly found in areas such as Australia, the Maldives, and many other regions. They are areas of natural beauty and are known for being popular with tourists and divers alike.
How are Atolls Formed?
Atolls, mesmerizing natural formations found in the world’s oceans, hold a captivating story of their own creation. The process of atoll formation begins with the growth of coral reefs. These reefs are built by tiny coral polyps, which secrete calcium carbonate skeletons, forming intricate structures over time.
As the coral colonies continue to grow and thrive in warm, shallow waters, they create a solid foundation for the atoll to develop. Over centuries and millennia, the volcanic island beneath the water’s surface gradually sinks, while the coral reef keeps growing upwards towards the sunlight. As the island subsides, a lagoon is formed in the center, encircled by a ring-shaped reef.
This ring of coral, with its vibrant ecosystem of marine life, acts as a natural barrier, protecting the lagoon from the open ocean’s powerful waves. The result is a breathtaking atoll, characterized by its unique ring shape, pristine lagoon, and the awe-inspiring biodiversity it nurtures. Atolls serve as both natural wonders and vital habitats, showcasing the remarkable interplay between geological forces and the delicate balance of marine ecosystems.
Here are five of the most popular atolls in Australia.
Bikini Atoll, located in the Marshall Islands of the Pacific Ocean, holds a unique place in history and continues to captivate the imagination of many. Known predominantly for its role in nuclear testing during the mid-20th century, this picturesque atoll boasts a fascinating yet haunting legacy.
Once a tropical paradise, Bikini Atoll’s pristine waters and vibrant coral reefs were transformed as it became ground zero for a series of atomic bomb tests. The tests, conducted by the United States between 1946 and 1958, forever changed the landscape and displaced the local inhabitants.
Today, Bikini Atoll serves as a stark reminder of the destructive power of nuclear weapons and stands as a testament to the resilience of nature, gradually reclaiming its splendor amidst the remnants of a tumultuous past. Though it remains uninhabited, Bikini Atoll attracts intrepid divers and history enthusiasts from around the world, who come to explore its underwater wonders and pay tribute to the atoll’s unique and complex history.
Atolls of the Abrolhos Archipelago
The Abrolhos Archipelago is actually located off the west coast of Australia. It is a mesmerizing collection of islands and coral reefs that form a unique ecosystem in the Indian Ocean. The archipelago is renowned for its stunning coral formations, abundant marine life, and rich maritime history.
The atolls in the Abrolhos Archipelago are formed through a combination of coral growth and geological processes, creating a series of circular or elongated reef formations surrounding lagoons.
These atolls provide a haven for diverse marine species, including colorful corals, tropical fish, dolphins, and seabirds. The Abrolhos Archipelago offers visitors a remarkable opportunity to explore its natural beauty, engage in snorkeling and diving adventures, and immerse themselves in the rich cultural and historical significance of the region.
This atoll is located in the Coral Sea, and it is the second largest of its type in Australian waters. Unlike many other atolls, Lihou Reef is shaped like a U, with an opening at one end.
The lagoon that is ‘inside’ the atoll is huge, around 100km at its widest point, which makes it stand out from many of the others, which are much smaller. While the atoll itself is large, the land area is not; in fact, there is less than 1km square of land available within. With this in mind, this atoll is best seen from a boat, or you might want to explore underwater by diving.
Mermaid Reef is one of the three atolls that join to make Rowley Shoals which are a cluster of reefs, lagoons and land masses that are located on the north west coast of Australia. Mermaid Reef is a diver’s paradise as there are so many underwater species to observe. Anyone who dives in these clear blue seas must be at an advanced level as the geography underwater, along with the depth of the dives makes it more difficult. Due to the amazing sea life which can be found in Mermaid Reef, the area is now a nature reserve.
Mermaid reef is a fantastic tourist location for diving.
This is the second of the atolls that make up Rowley Shoals and lays at the southerly tip of the shoals. It is around 16km long and 8km wide, making it one of the larger atolls in terms of land area. It has many different reef formations and two impressive lagoons that fill with water as the tides ebb and flow. There is an islet on the atoll that has a lighthouse on it which has been standing for more than 100 years.
This area is just over 22km away from Mermaid Reef and it is also known as Minstrel Shoal. It is around 15km long and 6km wide and it features many coral patches, a 2m high sand cay and dry areas which are revealed at different times of the day. There is a wonderful natural passage that you can follow which will bring you out into a lagoon that is breathtakingly beautiful.
You can get to Ningaloo Reef from Coral Bay and it is most easily reached by a short swim from the shore. You will find some of the most amazing underwater life at Ningaloo Reef that is only found in this part of the world. You will be able to swim with turtles, manta rays and even whale sharks in the clear, warm seas and it is an experience not to be missed. The colours of the reefs are nothing short of stunning and as soon as you go underwater you will feel as though you are in another world.
Visiting an atoll is something that you should do if you are in Australia. The diversity of wildlife that you will find there is out of this world and you will never see anything like this so close to home. If you are a keen diver check out the life under the water or if you prefer to keep your feet dry book yourself onto a glass bottomed boat for a view of what is going on under the waves.
Australian Atoll FAQs
What is the difference between an island and a atoll?
Difference between an island and an atoll: Islands are landmasses above water, often formed by volcanic activity or tectonic forces. Atolls are ring-shaped coral reefs surrounding a central lagoon, formed when a volcanic island sinks or erodes.
Does Australia have an atoll?
Yes, Australia has the Rowley Shoals, located off its northwest coast, known for its rich coral biodiversity and pristine underwater ecosystems.
What is the difference between a reef and an atoll?
Reefs are underwater ridges made of coral, rock, or other materials, while atolls are circular or elongated reefs encircling a lagoon, formed from sinking or eroding volcanic islands.
Where is the biggest atoll in the world?
The Suvadiva Atoll in the Maldives, spanning around 275 square kilometers, is the largest atoll globally, featuring numerous coral islands and a stunning lagoon.
What does an atoll look like underwater?
Underwater, atolls showcase clear, shallow lagoons surrounded by vibrant coral gardens teeming with diverse marine life, providing an awe-inspiring sight for snorkelers and divers.
How deep is the water in an atoll?
An atoll’s water depth varies, with shallower lagoons in the center ranging from a few meters to tens of meters. The outer rim of the atoll, where the reef is located, can have deeper waters extending hundreds of meters or more, influenced by tides, currents, and topography.
Jane Freeman is a travel blogger and digital marketer based in the UK. Jane splits her time between London during the Spring/Summer and Asia in the winter.