10 of the World's Most Spectacular Artificial Reefs

Artificial reefs are human-made underwater structures built to provide a stable habitat for marine life. Some artificial reefs are purpose-built cement and metal structures that are designed to promote algae and coral growth. Others are repurposed artifacts of varying shapes and sizes. Because coral will affix itself to most hard surfaces, objects like decommissioned ships and subway cars can serve as successful artificial reefs.

Artificial reefs are deployed in areas where the ocean floor is mostly featureless, and can revitalize the ecosystem in areas where little life was previously found. In many cases, the interesting marine worlds created by artificial reefs also serve as destinations for snorkelers and scuba divers.

Here are 10 of the world's most stunning artificial reefs.

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Redbird Reef

A diver inspects a submerged subway car covered with coral in a green-tinted seascape — United States EPA / Wikimedia Commons / Public Domain

Redbird Reef is an artificial reef located off the Delaware coast that is constructed mostly of decommissioned New York City subway cars. It covers 1.3 square miles of ocean floor, and sits about 80 feet below the water surface. Aside from the 714 subway cars, the reef is also populated with 86 retired tanks and armored personnel carriers, eight tugboats and barges, and 3,000 tons of ballasted truck tires.

Experts consider Redbird a highly successful example of an artificial reef. The sea floor in the Mid-Atlantic region is mostly featureless sand and mud, and the artificial reef provides vital habitat for a number of invertebrate species, like blue mussels and oysters. Since its installation in 2001, the reef has spurred the growth of 400 times more food for fish compared to the bare ocean floor.

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The Tank

A submerged tank in clear, light blue water — Dan Lundberg / Flickr / CC BY-SA 2.0

The Tank is an artificial reef made out of a single American M42 Duster tank. It rests on the ocean floor in Jordan's Aqaba Marine Park, beneath about 15 feet of crystalline water. The tank was purposely sunk in 1999 by the Jordanian Royal Ecological Diving Society to provide habitat for coral and sea sponges. Today, it supports a variety of marine life, including lionfish, sea stars, and shrimp. The reef also serves as a popular snorkeling and diving destination.

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USS Oriskany

A submerged ship covered in barnacles and algae with schools of fish swimming nearby — Gary McDaniel / Wikimedia Commons / CC BY 4.0

The USS Oriskany, a decommissioned aircraft carrier, found new purpose in 2006 as the largest vessel ever sunk to create an artificial reef. The Oriskany, which is 888 feet long and weighs 30,800 tons, rests 24 miles off the coast near Pensacola, Florida in the Gulf of Mexico. Before its sinking, the vessel was reviewed by the Environmental Protection Agency to ensure that all toxic substances on the ship were removed. Its surfaces are now slowly disappearing under marine life such as coral, mussels, and algae. Among divers who visit the carrier, it is now commonly referred to as the "Great Carrier Reef," a nod to Australia's Great Barrier Reef.

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Neptune Memorial Reef

A lion statue resting on the sea floor in front of other indiscernable objects — Todd Murray / Flickr / CC BY-SA 2.0

Located off the coast near Key Biscayne, Florida, the Neptune Memorial Reef is a vast 16-acre artificial reef designed to represent the mythical city of Atlantis. The reef is built of cement and metal structures that support coral and algae growth, and feature holes and arches for fish habitat. A 2012 study found that the reef was home to 56 fish species and 195 coral colonies of 14 species.

The reef also serves as an underwater memorial. Patrons can elect to have their cremated remains mixed with cement to become a permanent fixture in the reef.

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The Silent Evolution

A collection of underwater statues on the ocean floor, with a fish swimming above them — allenran 917 / Wikimedia Commons / CC BY 2.0

"The Silent Evolution" is an artificial reef that doubles as an art installation. Designed by Jason deCaires Taylor, the reef is a collection of 450 underwater figurines that rest of the seafloor in a national marine park near Cancún, Mexico. It's part of the Cancún Underwater Museum of Art, a broader collection of marine sculptures that are designed to improve the ecosystem and attract tourists to the area.

Taylor created the sculptures in an effort to increase awareness of the plight of coral and other fragile ocean life. It is easily accessible to visitors and serves as a popular destination for snorkelers and scuba divers in Mexico.

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The Pyramids

A gazebo structure with a pyramid-shaped roof lies on the ocean floor — Placebo365 / Getty Images

The Pyramids are a series of cement structures that serve as an artificial reef at a dive site in Jemeluk, Indonesia. In conjunction with stunning natural coral reefs found nearby, they foster a habitat for tropical fish and green sea turtles in calm, clear waters that are popular with divers.

The artificial reefs were installed by officials in Indonesia as an element of an initiative to protect the country's marine ecosystems. Part of the Coral Triangle, Indonesia's coastal waters are a hotbed of coral reefs and marine biodiversity, but have struggled with illegal fishing and coral die-off in recent years.

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Urban Reef

A stone house on the ocean floor covered in coral — Andy Blackledge / Wikimedia Commons / CC BY 2.0

"Urban Reef" is another of James deCaires Taylor's reef art exhibits, designed to resemble an underwater house. Like the human figurines of "The Silent Evolution," "Urban Reef" is located within the Cancún Underwater Museum of Art off the coast of Mexico. Taylor designed the house sculpture with input from marine biologists. It features open windows that lead into protected rooms and provide shelter for fish and other creatures.

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USNS Hoyt S. Vandenberg

An algae-encrusted American flag sits atop metal railings in a shipwreck — U.S. Navy / Wikimedia Commons / Public Domain

The USNS Hoyt S. Vandenberg, a World War II-era transport ship, is the second-largest artificial reef in the world after the Oriskany. The 522-foot-long Vandenberg was sunk off the coast of Key West, Florida in 2009. Researchers spent months combing the seafloor for an appropriate location where the ship would not impact natural coral reefs in the area.

The Vandenberg is a popular recreational diving site. Officials hope that in addition to supporting marine life, the artificial reef will reduce tourism pressure at nearby natural reefs, which are fragile and can be damaged when visited too frequently by recreational divers.

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Dakota Plane Wreck

Two scuba divers explore the wreckage of a plane on the ocean floor — mgokalp / Getty Images

A C47 Dakota military transport plane was intentionally sunk off the coast of Karaada, Turkey in 2008 to function as a dive site and artificial reef. Before reaching its new underwater home, the plane was in service as a transport plane with the Turkish Air Force. The plane, which has a wingspan of 96 feet, is just one of many artificial reef projects found along the Turkish coastline. Divers have reported that the plane now hosts a rich diversity of aquatic life, including giant groupers, one of the largest species of reef fish in the world.

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Reef Balls

Reef balls are not a singular artificial reef, but a specially designed cement structure that can be deployed to create artificial reefs around the world. Reef balls are hollow spheres with holes on their surface that attract fish species. They are built of a specialized nontoxic concrete that mimics the composition and pH of seawater to promote organism growth. In some cases, coral plugs are installed directly on the structures, to hasten the creation of a new marine habitats. More than 500,000 reef balls have been used to create some 4,000 new coral colonies in Asia, Africa, the United States, and the Caribbean.