The Bloop as it has come to be known, is an ultra-low frequency and extremely powerful underwater sound recorded in 1997 in a remote part of the South Pacific Ocean. Consistent with noises made by icequakes, the source of the noise is still a mystery, though Dr Christopher Fox believed that the Bloop may have been created by something living...
"[Dr Christopher] Fox's hunch is that the sound nicknamed Bloop is the most likely to come from some sort of animal, because its signature is a rapid variation in frequency similar to that of sounds known to be made by marine beasts. There's one crucial difference, however: in 1997 Bloop was detected by sensors up to 4800 kilometres (2982.582 miles) apart. That means it must be far louder than any whale noise, or any other animal noise for that matter. Is it even remotely possible that some creature bigger than any whale is lurking in the ocean depths?" - David Wolman (writing for New Scientist)
2. The Colossal Squid Exists
Believed to be the largest species of squid in existence, the colossal squid (from the genus mesonychoteuthis) can reach a length of 12-14 metres (39-46 ft) and a weight of 750kg (1650lb). Surviving at depths of 7000 feet, and known to prey on such underwater creatures as- wait for it- sperm whales (though these struggles are said to favour the whale just as often), the colossal squid is one of the most dangerous hunters of the deep.
3. 95% of the ocean is unexplored
While the entire ocean has recently been mapped out to a resolution of around 5km using radar from satellites, actual exploration is incredibly incomprehensive, with humans having seen only 5% of the deep blue.
Think of the incredible mysteries which could be solved by further sub-aquatic exploration, and the dangerous entities which might be disturbed...
4. The Mariana Trench is deeper than Mt Everest is high
Located in the Western Pacific Ocean, and reaching a depth of 10,994 metres (6.831 miles), the Mariana Trench is the deepest part of the world's oceans. By comparison, Mount Everest stands at 8,848 metres (5.497 miles) above sea level, meaning the deepest part of the Mariana Trench is 2,147 metres deeper than Everest is tall.
Discovered in 1875, it wasn't until 2012 that the deepest section of the Mariana Trench- the Challenger Deep- was finally traversed. This feat was achieved by the deep-diving submersible Deepsea Challenger, containing none other than self-confessed "king of the world" James Cameron- director of such oceanic classics as Titanic, The Abyss and, erm, Piranha II: The Spawning.
5. The longest mountain range in the world is underwater
The Mid-Oceanic Range, over 56,000km long, runs through the Atlantic Ocean and into both the Pacific and Indian Oceans.
Also on the subject of underwater mountains: Hawaii's Mauna Kea is taller than Mount Everest, when its submerged half is measured.
6. Two thirds of marine life is still "unidentified"
A study in the Current Biology journal in 2012 found that up to 1 million forms of life live in the ocean, of which we are aware of around 270,000. Though most of this life will be crustaceans, mollusks, worms and sea sponges, our lack of knowledge about aquatic life, coupled with how little of the sea we've actually seen, means that pretty much anything could be living down there... such as this:
7. Abyssal gigantism
Also known as deep-sea gigantism, this is the tendency for invertebrates and deep sea-dwelling animals to grow to much larger sizes than their shallow water relatives.
Squid, crabs and tube worms are known to have colossal deep-sea counterparts; there are even numerous mentions throughout history- mainly from spooked sea-farers- of giant, serpent-like eels...
8. The Japanese spider crab is a thing
The Japanese Spider Crab is the stuff of nightmares. With the largest leg span of any arthropod (reaching a terrifying 3.8 metres/12 ft), and claws which are known to do serious damage to anything which gets in its way, the spider crab is omnivorous, and is happy to feast on most creatures sharing its 500-1000ft deep habitat.
9. This Sunken Treasure is cursed
In 2010, self-confessed thrillseeker and treasure hunter Jay Miscovich allegedly bought a treasure map from a diver friend at a dingy bar in Key West, Florida, and which directed him to a shipwreck in the Gulf of Mexico.
There Miscovich uncovered the find of his life: "10s of thousands of emeralds in 70 feet of water", scattered from the wreck of the Atocha, a 16th-century Spanish galleon.
There was just one problem: after a 60 Minutes feature on the story aired, federal investigators began taking a keen interest in Miscovich's treasure, and soon Jay found himself under investigation for fraud. Three years passed in which Miscovich was forced to wait to cash in on the treasure, when without warning, Miscovich took his own life. Thus the mystery surrounding the treasure remains...
10. The Goblin Shark
The goblin shark is a true terror of the deep. It's often referred to as a 'living fossil', which is understandable when you take one look at its prehistoric appearance.
Dwelling in depths of 100 metres (330 ft), the goblin shark's most notable trademark is its jaw which- when opened to bite- far too closely resembles the monster from Ridley Scott's Alien. Wait for the 30 second mark in this video to see what we mean: