Covering more than 70 percent of the Earth’s surface, the lifeblood of our planet is most certainly the ocean. It ultimately supports all living organisms by regulating the temperature and driving the weather. As we have only explored a small portion of this vast space (to date only approximately five percent) much still remains to be seen and learned about what’s hidden below the surface of our beautiful deep blue sea. Underwater explorers have discovered marvellous and fascinating secrets of the ocean.

Some of these discoveries are natural occurrences like underwater rivers, canyons and jungles. Other things like man-made structures have intentionally been placed in the ocean and are known as artificial reefs. They are typically built to provide marine life with a stable habitat where there is generally a featureless bottom. These artificial reefs also control erosion, improve surfing and block ships passage. They can consist of anything from sunken tanks, tires, planes and subway cars to magnificent sculptures by artists. They have become some of the world’s most sought out dive destinations providing divers and in some cases snorkelers, with the opportunity of a lifetime. Now let’s take a look at some of these amazing natural and artificial underwater structures found around the world.

20 The Silent Evolution Of MUSA, Cancun

One of the World’s most unique and unforgettable museums is underwater just off the coast of Cancun. MUSA (Cancun Underwater Museum) is located in the Machones reefs off the coast of Isla Mujeres which is a Mexican island in the Caribbean sea. Created by Jason de Caires Taylor, an underwater sculptor and photographer, this museum draws over 750,000 visitors in a year and is easily accessible to snorkelers or divers. It features an awe-inspiring exhibit of 400 sculptures that mostly depict people seemingly frozen in time. Its purpose is to make people aware of the fragile ocean life, like corals for example.

19 The Tank In Aqaba Marine Park, Jordan

The Tank sits in only 6m of water off the coast of Jordan in the Aqaba Marine Park. With exceptional visibility of 25m+ which is a very important factor to a diver, the straightforwardly named ‘Tank’ is an American M42 Duster. It was cleaned up and sunk in 1999 by The Jordanian Royal Ecological Diving Society. It created an artificial reef that sponges, soft corals and colorful reef fish now call their home. Packed with invertebrates like shrimps, crabs and starfish in all the Tank’s little nooks and crannies, this is a diver’s paradise to watch all of the amazing marine life happening.

18 The Neptune Society Memorial Reef, Florida

Off the coast of Key Biscayne, Florida about three miles, there is a memorial site that serves as a kind of ‘cemetery’ for cremated remains. Inspired by the Lost City Of Atlantis, this artificial reef opened in 2007 and sits at a depth of 40ft and occupies a half-acre of space. Cremation ashes are mixed with cement to form the material that makes the reefs. Domes, arches, benches, roads, gates, columns and a lion are all part of this underwater city. Divers and boaters are welcome to the reef, but no fishing or lobster taking is allowed as it is considered to be a special management zone.

17 The Sunken ‘Fake’ Moai at Easter Island, Chili

We are all familiar with the famous monolithic statues of majestic Easter Island. Built by the natives in approximately 1400-1650 A.D. these huge iconic statues are scattered all around the island’s coastline. Known as moai, the squared human head statues weigh up to 86 tons each, and there are about 1000 of them. All of them, except one, sit on the island’s dry ground, but the one that is submerged off the coast isn’t exactly an ancient wonder. Sadly, it is just a prop from a 1994 Hollywood movie starring Kevin Costner. The fake moai is still a sight for sore eyes though and is on many divers bucket list.

16 Cayman Island Bronze Mermaid

Sitting in 55ft of water off Grand Cayman is a mermaid statue named Amphitrite, Siren of Sunset Reef. Sunset Reef is Sunset House Resort’s house reef where she was placed into the water during a dedication ceremony in 2000 which was hosted by the resorts general manager. Created by Simon Morris, a Canadian artist, the bronze statue weighs 600-pounds and is 9 feet tall. Her name was chosen in a contest where a 14-year-old Philadelphia girl submitted the winning name and won a free trip to Grand Cayman. Her name, Amphitrite, comes from mythology, and she was the queen of the seas. She was married to Poseidon, the lord of the oceans.

15 Museo Atlantico Underwater Museum, Spain

Considered to be Europe’s first underwater museum, Museo Atlantico sits in the pristine waters of the Atlantic seabed at 12 meters deep. Just off the coast of Lanzarote, Spain, this ‘exhibit’ is composed of more than two hundred pH-neutral cement sculptures that are life-size human shapes placed in a circle. Bahía de Las Coloradas, where this exhibit sits, has become a tourist and cultural attraction for divers from around the world. Covering approximately a 2,500 square meter area, the structures, in time, will help marine life flourish and will also aid in the island’s species being able to reproduce.

14 Yonaguni Monument, Japan

This giant rock formation located off the coast of Japan, is approximately a hundred kilometers east of Taiwan and has baffled scientists since it’s discovery in 1987. Not sure whether it’s a man-made or artificial structure, what is known is that it’s composed of mudstone and sandstone with all sorts of interesting details for divers to explore. The giant rock slab is 90 feet tall, nearly 130 feet wide and 500 feet long. This enormous structure’s top rests only 16 feet from the surface of the water and despite the strong currents, is a very popular attraction for divers. Even today the origin of the Yonaguni Monument is disputed but what can’t be disputed is that it’s an amazing sight to see.

13 Grenada Underwater Sculpture Park

In the West Indies of the Caribbean, sits the island of Grenada which has an underwater sculpture park that is a must see. Creator Jason deCaires Taylor, who I am calling the ‘father of underwater sculptures’ placed 68 different sculptures to visit and they are dispersed in the shallow waters off Moliniere Point. With the deepest attraction at only about 25 feet, it is easy for snorkelers as well as divers to be able to see the structures. In 2006 this popular modern wonder was opened to the general public for a $1 USD conservation fee to visit the park.

12 Junkyard Reef, Koh Tao, Thailand

Known as “Turtle Island”, Koh Tao is part of an Archipelago on the Gulf of Thailand’s western shore. The island’s official population in 2006 was only 1,382 and its economy is focused exclusively on tourism, especially diving. As the name implies, Junkyard Reef is exactly that - Junk. Anything that would not harm the environment was sunk down for fish to make new homes out of. Things like toilets, cars, gym equipment and even a bridge. It’s a shallow place with a varying depth of about 10-12 meters depending on the tide. The visibility like most places varies as well throughout the seasons and range from 5-20 meters.

11 The Subway Car Artificial Reef, Delaware, USA

At 16 nautical miles off the coast of Delaware sits hundreds of New York City subway cars that have been retired to the ocean’s bottom to find their second home. Resting at 80 feet underwater they are transforming "a barren stretch of ocean floor into a bountiful oasis, carpeted in sea grasses, walled thick with blue mussels and sponges, and teeming with black sea bass and tautog" according to the New York Times. A whopping 666 subway cars have found their way to the ocean floor and the fish appear to like the spaciousness of them and the car's weight ensures that they will stay anchored securely to the bottom.

10 Buddha Statue In Bali

Bali is the quintessential place for visitors to have the eat, pray, love experience, but off the beaten path is a place where divers can go to see gorgeous walls of corals and the underwater Buddha. The 8.2 ft tall Buddha statue sits in between several stupas which are structures that are dome-shaped and erected as a shrine for the Buddhist. The underwater Buddha is located in the Ceningan channel right at the entrance and it is facing North. An organized day tour in groups costs about $95 USD but a local guide can get your there for a more relaxed experience without the crowds for just a bit more money.

9 NASA’S Tektite, Virgin Islands, U.S.

Located off the coast of St. John, Virgin Islands was an underwater NASA laboratory that housed divers in 1960-1970. Sponsored nationally and considered to be the first scientists-in-the-sea program, General Electric Companies Space Division designed and built the Tektite capsule. At a depth of 15 meters, the habitat is seated on a rectangular base and it consists of two metal cylinders joined together by a flexible tunnel. The white, 6 meter high, 4 meters in diameter cylinders look like a pair of silos. Today all that's left of the Tektite is its concrete moorings, but it is still visually interesting sight worth the visit.

8 Aquarius Research Facility, Florida Keys

There is only one operational permanent underwater research lab in the world and it is located in the Florida Keys National Marine Sanctuary. Just a few miles south of Key Largo, the underwater habitat sits on the ocean floor in 62 feet of water and is right next to Conch Reef. Being it is in a marine sanctuary, a protected area, the fish and coral population are much healthier than in other underwater places. It's about the size of a school bus and can fit about 7 people in at one time. Its used as a training facility by researchers, Florida Institute University students, NASA and the Navy, but you can pay $4,500. USD to spend a night in it during FIU’s special expedition period.

7 Ithaa Undersea Restaurant, The Maldives

You don’t need to be a certified scuba diver or even a snorkeler or swimmer to be able to enjoy this underwater structure. It’s called Ithaa, and it is the world’s only all-glass undersea restaurant. In 2014, the New York Daily News rated Ithaa, "the most beautiful restaurant in the world". It rests at 16 feet below sea level and offers its patrons a panoramic view of the beautiful coral gardens that surround it. It serves a contemporary European cuisine for a four-course lunch or a six-course dinner. You will pay the price for its underwater ambiance, however, as lunch for two can cost around $500. USD.

6 The Sunken Pirate City Of Port Royal, Jamaica

The depiction of Port Royal in The Pirates of the Caribbean is pretty accurate. In its heyday, Port Royal was called “the most wicked and sinful city in the world” and infamous for it pirates, ladies of the evening and of course its black-out inducing Kill Devil Rum. In 1692 a devastating 7.5 magnitude earthquake swallowed up the city and today most of its remains lie under 40 feet of water. Divers have been exploring the submerged city since the 1950’s but today you need special access from the government to dive the restricted ruins. Many of the buildings are still intact and it was designated as a National Heritage Site in 1999 because of its archaeological wonders.

5 The Lost Villages of Ontario, Canada

In 1958 to create St. Lawrence Seaway in Ontario, Canada, nine communities were intentionally and permanently submerged underwater. It was very controversial at the time because many businesses and families were given market value compensation to relocate, but felt it was insufficient due to already depressed values from the Seaway plan. The Seaway’s purpose was to make the waterways deeper for easier access to ports along the great lakes and to generate hydropower for cheap electricity. Today it is a popular dive destination as St. Lawrence Parks Commission offers many access points to be able to explore the underwater history.

4 The Sunken City Of Dwarka, Gulf of Cambay, India

One of the best studied underwater places in India are ruins in the Gulf of Cambay known as Dwarka. Considered to be a sacred place in the Hindu religion, this ‘fabled’ city of Lord Krishna is estimated by scientists to go back in time as far as 9,000 years. In 1988 a detailed excavation and exploration were started on this sunken city where grids of streets, sandstone walls and some evidence of a seaport was found resting in 70 feet of water. India’s National Institute of Ocean Technology was conducting a pollution survey when they discovered the ruins by chance. Things recovered from the site like pottery, beads, sculptures and even human teeth and bones were carbon dated to determine its age.

3 China’s Mysterious Underwater City

Under the water in Qiandao Lake, China is one of the most spectacular ruins in the world. Built during the Eastern Han Dynasty, these almost perfectly preserved temples with their monuments that have intricately detailed carvings on them and can be dated back to the 2nd century. This sunken city is known as Shi Cheng which loosely translates to Lion City because the city was surrounded by the five Lion Mountains. In 1959 the government built a dam for a hydroelectric power and purposely flooded the city. It now sits at a depth anywhere between 85 and 131 feet and is a popular dive attraction.

2 Cleopatra's Alexandria, Egypt

Discovered off the shores of Alexandria, Egypt is one of the world’s richest archaeological sites that have been lost for 1,600 years. Cleopatra’s empire is believed to have been sunk by an earthquake and tsunami. The entire city was completely submerged with all its statues, columns and artifacts largely intact. Things like the palace foundation, red granite columns, shipwrecks, sphinxes and statues of the goddess Isis have been discovered. Archaeologists have been excavating the site since 1998 but there are still many artifacts for divers to see. Divers can get lots of bottom time because it's in shallow water (about 5-8 meters) but the visibility is pretty bad.

1 The Sunken City In Southern Greece

Pavlopetri is a small village in the Peloponnesus region of southern Greece and is where the oldest known submerged city in the world resides. Found in about 4 meters of water, this city is not an ordinary archaeological site because it is very much intact and it is 5,000 years old. Besides its age, what's surprising about the ancient city is that its design surpasses many of today's current cities. It is estimated the city sunk around 1000 BC from an earthquake and was inhabited prior to 2800 BC. The area it occupies extends for about 9 acres and it consists of at least 15 buildings.