5 of the strangest secrets lurking in our oceans

You’d have thought that since our oceans make up a massive 70% of the earth, we’d know a little bit more about them, right? Well, you’d be wrong there. In fact, we know more about the dark side of the moon and the outer limits of the solar system than our own oceans, with experts suggesting that as much as 80% remains unmapped, unobserved and unexplored.

So, what really lurks beneath the deep blue? Here are just a few of the strangest secrets and baffling mysteries to come out of our oceans…

1) The Underwater Falls

There’s no denying that Mauritius, a tiny island nation nestled in the tropical Indian ocean, is one of the most beautiful places on earth. It’s also one of the most mysterious – home to the scientifically baffling underwater falls.

However, it’s not exactly water that’s cascading down these falls, it’s sand and other sediment. The illusion of a waterfall is creating by a giant, deep ravine that bisects an otherwise shallow shelf, laden with sediment. The sand and sediment are sent tumbling into this ravine, creating the waterfall illusion.

While this example in Mauritius may be one of the most breath-taking, there are several other instances throughout the world that actually do involve water – real underwater falls. The largest of them is the Denmark Strait Cataract, located in the North Atlantic Ocean. It’s far larger than Angel Falls, the largest waterfall in the terrestrial realm, and sees over 135 million cubic feet of water tumble down an 11,500 foot drop, every single second. The cascade of water is caused by colder, more dense water, flowing under the surface-lying, warmer and less dense water – a bit more of a complicated process than water simply falling from a cliff face on land.

2) The Milky Sea Phenomenon

Another event with roots in the Indian Ocean, the Milky Sea phenomenon, has been witnessed by sailors for over 400 years, with reports of milky glowing waters stretching for miles, sometimes beyond the horizon. The Indian and Chinese folk tale soon found its way into western popular culture through Jules Verne, author of ‘Twenty Thousand Leagues Under the Sea’, in which he depicts this glowing, ‘milky’ sea during one of the most popular scenes in the book.

It may have its roots in maritime folklore and science-fiction writing, but that doesn’t make the phenomenon any less real. In 2005, Dr Steven Miller of the Naval Research Laboratory in Monterey, California, led a team of scientists tasked with explaining this baffling phenomenon. With the aid of satellite systems and water samples, the scientists located these glowing patches of water, discovering that tiny bioluminescent bacteria were the guilty party at large.

Why these bacteria gather in such huge number – in the region of 40 billion trillion individuals, as reported by ScienceDaily– is still unknown but Miller and his team suggest that they congregate in an attempt to colonize even more organic material. By attracting fish with their bioluminescence, they are ingested and sent straight into the fish’s digestive tract, finding it to be the perfect place to live and reproduce, cultivating the next generation of bacteria.

3) The Bloop

Heard across hydrophones planted in the Pacific Ocean back in 1997, the Bloop was a super-low frequency sound that was picked up at several underwater listening stations some 5,000km apart from one another. Following the discovery, many theories emerged surrounding the sound’s ‘organic’ and ‘natural’ sound profile, leading conspirators to suggest that it was evidence of a giant creature of truly mythical proportions. 

Experts entertained the theory at first, investigating what size the creature would have to be to produce a sound of such epic proportions. Upon learning that the creature would have to be around the size of the Eiffel Tower to produce such a sound, they were prompted to investigate other lines of investigation. This led them onto the idea of underwater earthquakes, more specifically, icequakes.

Robert Dziak, world-leading seismologist at the NOAA, explains the reasonbehind the booming ‘Bloop’:

“Ice breaking up and cracking is a dominant source of natural sound in the southern ocean. Each year there are tens of thousands of what we call ‘icequakes’ created by the cracking and melting of sea ice and ice calving off glaciers into the ocean.”

So, there you have it, you can call off the Kraken witch-hunt.

4) Deadly Underwater Lakes

While it seems impossible that lakes – and rivers – could lie at the bottom of the oceans, it’s both entirely natural and actually quite common. Fast-flowing underwater rivers are found throughout the oceans, the largest of which is located right under the Black Sea. It’s actually the sixth-largest river (by volume) in the world, a whole 350x larger than the River Thames and up to 150-feet deep in places. 

These rivers are heavily laden with salt, making the water in them a lot denser than the surrounding water. They’re thought to be carriers of massive swathes of sediments and minerals, as well as vital for supporting some oceanic life. 

Underwater lakes are created under similar ‘salty’ physics. As seawater seeps up through thick layers of salt, the layers are weakened and collapse, resulting in depressions. As the salty water is denser, it then settles in these depressions, forming the underwater lake. Beautiful and baffling they may be, but these lakes are some of the most deadly places in the ocean, especially for unsuspecting ocean-faring creatures. The salt creates a soupy brine that poisons any creature that dares to venture in, causing them to experience toxic shock and violent convulsions before meeting their bitter, salty end.

5) Red Tides

No, it’s not a re-run of Jaws, or a new maritime horror film – the waters in coastal areas around Florida, China and Japan really do turn a shade of red. These red waters occur when colonies of algae grow out of control,starving the water columns of oxygen and producing harmful toxins that wipe out all the fish, shellfish, marine mammals and even birds living in the area.

These red tides are particularly common along Florida’s Gulf Coast, occurring nearly every summer season. Not only do the tides have a damaging affect on those in the water, they can also affect the surrounding air quality too, making it difficult for people to breathe. 

A number of factors can cause algae to bloom, some natural, others not. Unfortunately, a lot of these harmful red tides are created by our own hands, sewage and pollution – runoff and effluent from farms and large agricultural industries, in particular – promoting vast population booms in these tiny marine organisms.



The oceans need a whistle-blower – you.

While some of the strange ocean secrets on this list are entirely natural, and staggeringly beautiful – the underwater falls in Mauritius being the perfect example – many are scary, foreboding events catalysed by our own doing. The more ‘Bloops’ we record, the more icebergs are detaching from our shrinking ice sheets and the more red tides we observe, the more pollution is being pumped directly into our coastal waters. 

It’s time we lifted the lid on a lot of these ocean mysteries and exposed them for what they really are – products of our own mess. Mess needs cleaning and there’s no better marine clean-up charity around than 4Ocean. Make sure you head over to their website to learn all about their ocean-cleaning initiatives, or even purchase one of their bracelets– each one pulling a pound of waste from the world’s waters.

Will Newton