The ocean floor is home to diverse geological landscapes, from mysterious sinkholes to underwater waterfalls. Let us dive into some of the most unique underwater formations that have captivated human imagination and sparked our curiosity.
Great Blue Hole, Belize
The Great Blue Hole is a natural wonder off the coast of Belize. This massive underwater sinkhole is located in the center of the Lighthouse Reef Atoll within the Belize Barrier Reef Reserve System.
Now a UNESCO World Heritage Site, it was once a dry cave, formed during the Ice Age when sea levels were lower, and eventually collapsed and filled with water. The iconic sinkhole is approximately 300 meters in diameter and 125 meters deep with crystal-clear waters and beautiful stalactites (formed by dissolution of limestone rocks by acidic water).
It is the world’s largest natural formation of this type.
First made famous by the renowned French oceanographer and marine biologist Jacques Costeau in 1971, the Great Blue Hole has since attracted visitors and divers from around the world.
This is one of the planet’s most unique dive sites, offering a surreal experience with its deep blue waters, and diverse marine life, including candy-coloured corals and vibrant tropical fish including whale sharks. Excursions to the hole usually lasts around 10-12 hours, with stops for snorkeling, diving and sunbathing at white sand atolls along the way.
Only experienced divers are allowed to explore this underwater formation due to the complexity and depth of the dive. But everyone can swim over the hole, or go for a flyover experience.
Flying over the Blue Hole gives you an amazing view of the entire reef system.
Underwater Waterfall, Mauritius
Mauritius, the island nation in the Indian Ocean, is home to a natural hidden gem — the underwater waterfall.
Lying offshore of Le Morne Peninsula to the southwest of Mauritius, this geological phenomenon is actually a fascinating illusion of nature.
The islands in this region, known as the Mascarene Islands, were formed by volcanic activity under the ocean some eight million years ago. These islands are on top of a submarine plateau, also known as the ocean shelf. The optical illusion of an underwater waterfall is created by layers of sand and silt sediments being pushed down by ocean currents over the edge of the plateau, giving the impression of a cascading waterfall.
This drop-off of sand and silt plunges to depths of over 4,000 metres and with various hints of blue, it almost looks like part of the water is flowing within itself.
This stunning sight is best observed from the air. You can book helicopter tours or charter a private plane to fly above the island and get a bird’s-eye view of the waterfall.
Mariana Trench, Pacific Ocean
Situated in the western Pacific Ocean, the Mariana Trench lies between Hawaii and the Philippines near the small island of Guam. The Trench is like a crescent-shaped dent in the floor of the Pacific, formed by tectonic movements where the Earth’s crust is pushed downward into the mantle. As a result, the Pacific Plate is being pushed under the Mariana Plate. The trench is over 1500 miles long with an average width of around 43 miles. Its southernmost point is known as the Challenger Deep which sits 11,000 meters below sea level and is believed to be the deepest point of Earth. The depth is even more than Mount Everest if it were placed in reverse below the ocean.
The place is totally dark with temperatures just above the freezing point. Yet, this extreme environment supports unique life forms, including bioluminescent creatures and microorganisms that survive without sunlight. Mineral deposits are also being found in these extreme pressure conditions.
US naval officer Don Walsh and Swiss oceanographer Jacques Piccard were among the first to reach the bottom of Mariana Trench, back in 1960. However, it was made popular when the famous Canadian filmmaker and explorer James Cameron made a solo journey to the abyss in 2012. Since then, a handful of others undertook the daunting expedition as well.
Cenote Angelita, Mexico
Cenotes are naturally formed water pits or sinkholes found across Mexico’s Yucatán Peninsula. These are created when a limestone bed collapses exposing ground water underneath.
Cenote Angelita is one of the most popular sinkholes in Mexico for its distinctive trait – it appears as a river flowing through the ocean. It was discovered by a marine photographer named Anatoly Beloschin. This illusion of an underwater river is created by the layering of freshwater and saltwater, having different densities.
At around 30 metres deep, this river is covered by a thick cloud of hydrogen sulphide. Fallen tree branches are found along the shoreline and the water has a greenish hue, often covered with brown leaves and pollen. Mussels are the only life forms found in the cenote, as unlike other marine creatures, they can survive in toxic environments without sunlight.
Cenote Angelita is a popular spot for scuba diving and snorkeling.
Yonaguni Monument, Japan
The Yonaguni Monument, situated off the coast of Yonaguni Island in Japan, is a mysterious underwater rock formation. It was discovered by scuba diver Kihachiro Aratake back in 1986, while exploring the waters off the south shore of the island.
The rectangular monument measures around 100 meters by 60 meters and stands about 25 meters tall.
Since its discovery, the Yonaguni Monument has sparked debate about its origins. While some believe it is a natural formation, others argue that it is a man-made structure. The monument, with its massive rocks with sharp edges, angular structures, terraces, and what appear to be steps, certainly looks man-made and some believe it to be the remains of an ancient civilization. But there is a problem. Scientists believe the formation is thousands of years old, dating back to a time when humans couldn’t have possibly built it. They suggest it formed naturally over the years, with ocean currents slowly shaping its structure.
Regardless of its origin, it remains an intriguing and beautiful underwater site, and a favourite spot for scuba divers. The Yonaguni Monument is in shallow waters, but strong currents can be a challenge.
[AI picture generated by Gemini]
