Manmade Reefs

Did you know that not all coral reefs form naturally? There are underwater locations around the globe where artificial reefs have been created, both intentionally and unintentionally. Let’s start at one of the largest shipwrecks in the Caribbean—the SS Antilla.

[Tap and drag to look around the reef]

This ship began her maiden voyage from Germany in July 1939 and was in the Caribbean when the events of World War II began. The crew aboard the Antilla sabotaged the ship rather than surrender to the enemy. 

An artificial reef is a manmade structure found underwater which can mimic the characteristics of a natural reef. Submerged shipwrecks are the most common form of artificial reef, like the SS Antilla shipwreck in the Caribbean.

After the SS Antilla sank, larvae of coral, sponges and other marine organisms attached themselves to this new structure. Over time, the shipwreck has become encrusted in corals and sponges, transforming into a habitat for numerous marine creatures. 

Have you ever visited a museum underwater? A unique combination of art and environmental science, this unusual attraction near Isla Mujeres was created intentionally and is surely one of the most extraordinary scenes to find beneath the sea. 

The sculptures in the museum are made out of special environmentally-friendly material which deliberately promotes marine life. Microscopic organisms such as coral larvae drift onto the hard surfaces and colonize them. Where possible, artificial reefs like these are placed downstream of an already thriving reef.

The statues are designed with many gaps and crevices to offer fish and other marine creatures protection and places to call home. You can see a stripey Sergeant Major fish hiding between the statues here.

Thousands of tourists come to Cancun and Isla Mujeres every year to see the natural coral reefs. The underwater museum creates another attraction for the tourists, relieving tourism pressure on the natural reefs nearby, and potentially boosting their health.

Where better to look for artificial reefs than Bermuda, known for being the shipwreck capital of the world. The waters surrounding Bermuda are a legend of mystery, being associated with many disappearing ships and strange occurrences in years gone by. 

There are hundreds of shipwrecks in this vicinity, and we will be exploring one of them, the Mary Celeste.

The Mary Celeste was a paddle steamer which sunk in 1864 after being used to run ammunitions and supplies during the American Civil War. The wreck sits in 17 metres (55 feet) of water and one of the huge paddle wheels is still clearly visible.

Bermuda’s coral reefs are the most northern coral reefs in the Atlantic Ocean. They’re unique because they are dominated by brain corals, which usually only occupy 5-10% of the coral cover elsewhere in the nearby Caribbean reefs. 

Another shipwreck, another artificial reef. The USAT Liberty was a 394-ft-long ex-American cargo ship which now rests just off a rocky Tulamben beach in northeast Bali, thriving with marine life. 

The Liberty was torpedoed by a Japanese submarine in the Lombok Strait in 1942 and made it to Tulamben where it was beached. In 1963, nearby volcano Mount Agung erupted, and the earth tremors pushed the vessel into the sea.

These days, the shipwreck is a bustling hub of marine life. You can see here a congregation of bumphead parrotfish hanging around the wreck—they use their large, beak-like teeth to graze algae off the surface of the reef. 

 The Liberty shipwreck is a massive hit with scuba divers and is considered one of the top wreck dives in the world, mainly because it has attracted so much marine life, but also because it’s very conveniently close to shore. 

Some parts of the wreck are so covered in marine life, you wouldn’t even be able to tell it used to be a ship! Look at all the colourful species encrusted onto the structure here. 

On our expedition to manmade reefs we have to visit one of the most famous shipwrecks in the world—the SS Yongala. In 1911, this luxury passenger vessel disappeared in a tropical cyclone south of Townsville, Australia. None of the 122 people on board survived.

The ship’s location was a mystery until the wreck site was discovered in 1958. 

Even though the shipwreck is over 100 years old, much of the ship’s structure is still intact. The ship is 109 metres long and lies 30 metres deep, although the upper section is only 16 metres below the surface of the water. 

Since sinking, the ship has become encrusted in many different coral species and is now an artificial reef habitat brimming with life. There’s a strong current running over the shipwreck, which attracts an abundance of marine life of all sizes. 

The original in Italy, a replica in Grenada, and this example in Florida. 

The statue, which is made of bronze, is slowly but surely being colonized by encrusting coral, sea fans, and other marine creatures. It is becoming a part of the nearby coral reef. 

There are many reasons why ships can end up as a wreck on the ocean floor; some are sunk deliberately, and others, like the Indonur, in Karimunjawa, Indonesia, sink by accident. 

A Dutch steamship, the Indonur sank in 1963 after the captain mistook a fire on the beach to be the lights of Semarang, a port city in Indonesia, and went full speed into the reef. 

The huge steel plates and riveted steam boilers of the Indonur now house a variety of reef fish and coral life. The artificial reef grows bigger and bigger each year as a result. 

When a ship sinks, this new underwater habitat is quickly utilized by fish seeking shelter. Corals, which are composed of small delicate polyps, develop more slowly because they need to attach and grow. 

Over a period of many years coral will cover the shipwreck’s surface and the different colonies of coral will start competing for space. The more time that passes, the more the artificial reef will resemble a natural reef.