Over 1 million fish, marine mammals, and invertebrate species depend on coral reefs for habitats, camouflage, and food.

The National Oceanographic and Atmospheric Administration estimates that US commercial and recreational fisheries valued at $200M depend on coral reefs, which provide up to $1.8B in flood protection by absorbing 97% of wave energy.

The first coral reefs formed hundreds of millions of years ago from the carbonate skeletons deposited by hard corals.

Explore a map of coral reefs around the world and the extent of coral bleaching.

The world's largest coral, as seen from space

The world’s largest individual coral colony—measuring over 100 feet wide and 100 feet long—was discovered in the Solomon Islands. This coral is so large it can be seen from space, and is estimated to be between 300 and 500 years old. The coral's size and health provide hope amidst a global coral bleaching crisis, wherein three-quarters of coral reefs have experienced significant bleaching in recent decades. See the photos from space and learn more here.

From 2023 to 2025, coral reefs experienced their fourth global bleaching event and the largest such event through 2025.

Deep water corals—located throughout the world's ocean basins at depths beyond 200 meters (660 feet)—slowly build small coral gardens in the dark with the help of underwater worms.

Why are coral reefs important?

Coral reefs are vital ecosystems that millions of people and countless species depend on. This two-minute video from London's Natural History Museum looks at the ecological and economic significance of coral reefs, including their biodiversity and...

Explore the history, structure, and species of Australia's Great Barrier Reef with this interactive journey narrated by Sir David Attenborough.

Take a 3D underwater trip near the Great Barrier Reef

The Great Barrier Reef is the world's largest coral reef system, comprising more than 900 islands and almost 3,000 individual reefs. This video lets you tag along with divers as they explore the reef off the southern coast of Lady Elliot Island in full 3D (use the direction buttons in the upper left of the video, or your keypad).

The three types of coral reefs—fringing, barrier, and atoll—are categorized by where they form.

According to the International Union for Conservation of Nature, as of 2025, there are over 18,000 endangered animal species worldwide, with the share of fish, insects, mollusks, and reptiles increasing since 2007.

Scientists have found that the Great Barrier Reef's microbiome includes an estimated 362,802 distinct viruses and 876 distinct bacterial and archaeal species—584 of which had never been documented before 2026.

Watch a diving expedition through the world's longest coral colony, which spans more than a football field and whose exact location is kept secret for its protection.

The CCZ is believed to harbor trillions of dollars of valuable minerals and thousands of undiscovered species

Located between Hawaii and Mexico and spanning an area larger than the European Union, the Clarion-Clipperton Zone is the world's region with the most contracts awarded to groups seeking to extract valuable metals by collecting polymetallic nodules. Conservative estimates suggest that 21.1 billion tons of polymetallic nodules exist in this abyssal plain, but about 90% of the species in the area are unknown to scientists.

Scientists explore innovative solutions to protect coral reefs

As coral reefs are under increasing stress due to climate change, pollution, and other factors, scientists are employing creative solutions to save these crucial marine ecosystems. This National Geographic article explores the various scientific...

Coral reefs are built by thousands of coral polyps—tiny animals whose mouths both consume food and expel waste.

Through coral IVF, researchers have collected coral eggs and sperm from healthy reefs, grown baby corals in lab pools, and then released them to help repopulate damaged or lost reefs.

Can coral live in cold water?

Dive deep beyond the sunlit coral reefs, and you'll discover a world of deep-sea corals. This article from the National Oceanic and Atmospheric Administration (NOAA) explores the ecosystems of deep-sea corals found way below the water's surface....

Coral reefs get their colors from zooxanthellae—photosynthetic algae that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

Artificial coral reefs have been 3D printed from nontoxic, biodegradable terracotta clay, which coral polyps have used as a foundation for rebuilding marine ecosystems.

Mangrove forests can store up to four times as much carbon as other forests and protect inland areas through complex root systems that absorb wave energy and hold mud and soil in place, contributing to their status as keystone species.

Inside Australia's National Sea Simulator, scientists are cross-breeding coral species and using CRISPR to genetically engineer heat-resistant corals to withstand warming reefs worldwide.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

View a map of the distribution of mineral resources on the seafloor

Polymetallic nodules are found in regions near the middle of the Pacific Ocean, along the eastern coast of South America, and along the western coast of Africa, while cobalt-rich crusts span significant portions of the Pacific tropics east of the Philippines. Polymetallic sulfide deposits occur at tectonic plate boundaries, including areas within national jurisdictions.

View a collection of glass sculptures of corals threatened by fishing and deep-sea mining.

An analysis of fossilized reefs from northern Africa and Germany suggests that shallow water corals and photosynthetic algae formed the mutualistic partnership seen today between 419 and 359 million years ago.

Explore coral reefs in Google's "street view"

Expanding its mission to map the world, Google Maps partnered with The Catlin Seaview Survey to introduce the first-ever underwater panoramas, making oceanic marvels like the Great Barrier Reef accessible to everyone. With Google Maps, the public...

Research has found that when their symbiotic algae are not producing oxygen via photosynthesis, corals twirl hairlike structures to circulate water and draw oxygen into their outer tissues.

Coral polyps reproduce via broadcast spawning, where entire reefs simultaneously release reproductive cells for about one hour, once a year.

Synthetic pheromones may protect coral reefs by attracting their predators

Researchers in Australia and Japan have developed these nontoxic chemicals to attract crown-of-thorns starfish, which consume corals that make up the Great Barrier Reef. As of 2026, synthetic pheromones have been shown to be effective in lab trials, and future field trials will attempt to lure starfish into areas for mass removal.

Fungi have been used to restore island habitats in the central Pacific

After removing 1.5 million invasive coconut palm trees and eradicating the black rats that fed on them, as well as seabirds and crabs, conservationists working with the US Fish and Wildlife Service identified areas where fungi could be transplanted to provide nutrients to native trees. These trees serve as nesting sites for seabirds whose guano nourishes coral reefs.

Take an interactive tour through Australia's Great Barrier Reef, featuring spherical panoramas of marine wildlife, including manta rays, loggerhead turtles, and bottlenose dolphins.

View a collection of images and videos of coral reefs from around the world.

Climate change threatens coral reefs by disrupting the symbiotic relationship between corals and algae due to rising ocean temperatures.

As of 2026, the Great Atlantic Sargassum Belt is the world's largest macroalgal bloom, with seaweed stretching from the Caribbean to West Africa.

To protect the symbiotic algae they rely on for food, some corals absorb ultraviolet radiation and re-emit it as visible light, which these algae can photosynthesize.

Niagara’s bedrock holds 440-million-year-old coral fossils

The Lockport Dolomite that caps Niagara Falls is composed of fossilized coral reefs from a tropical sea that once covered the region 440 million years ago.