7 Most Bizarre Underwater Discoveries Nobody Can Explain
These mysteries run deep.
Given that around 70% of our planet is covered in water, it's hardly surprising that untold mysteries and amazing phenomena have been discovered beneath the waves, from ancient shipwrecks to thriving ecosystems.
The modern age of deep-sea exploration dates back to the late 1700s when French scientist Pierre Simon de Laplace calculated the depth of the Atlantic by measuring tidal motions on the Brazilian and African coasts, but it took mankind several centuries to truly conquer the oceans, and even now much of their depths remain uncharted.
In 1960, a research bathyscaphe called the Trieste became the first manned vessel to reach the bottom of the Challenger Deep in the Pacific Ocean's Mariana Trench near Guam, the deepest known point in the Earth's seabed hydrosphere.
This was a milestone for deep-sea exploration, but the discoveries haven't stopped there, with researchers having stumbled upon all kinds of weird and wonderful phenomena, not just in our oceans, but the depths of our rivers and lakes too.
From mysterious stone structures, to lifeforms that don't play by the usual rules, here are the most bizarre and mysterious things ever found during deep dives.
Honourable Mention: A Sunken Sculpture Park
Though not strictly unexplained (and hence why it's included as an honourable mention only), this entry was just too intriguing not to include.
The deep-sea gallery of sculptures in the Molinere Beausejour Marine Protected Area of the Caribbean Sea, off the coast of Grenada, gets an honourable mention for inspiring no less awe than some of mankind's more mysterious aquatic discoveries.
Located between four and five metres deep, the collection of statues is designed to enhance a conserved section of the ocean and highlight the way nature makes a permanent mark on the physical world over time.
Many of the sculptures, which includes life-sized casts of local children, are covered in sea vegetation and barnacles, and have been a hit with scuba enthusiasts for years.
The artwork has also encouraged marine life to take up residence in this stretch of the Caribbean Sea and thus proved beneficial to the environment.
7. An Aquatic Stonehenge
A strange stone formation with more than a passing resemblance to Great Britain's Stonehenge lies at the bottom of Lake Michigan. The monoliths' origins are unknown, but they are thought to be thousands of years old.
The site was uncovered by Mark Holley, a professor of underwater archaeology at Northwestern Michigan University College, and his colleague Brian Abbot in 2007 while they crossed the lake in a ship loaded up with sonar equipment, but the discovery has thrown up more questions than answers over the years.
The plot thickened when a carving of a mastodon, a distant relative of the elephants that's been extinct for over 10,000 years, was discovered on one of the pillars, suggesting its origins could stretch all the way back to the last ice age.
A similar monolith has also been discovered in Europe, this time in salt water off the coast of Sicily, although experts believe these stones once served as a primitive form of lighthouse technology, illuminating the way for seafarers in a bygone age.