The Frontier Below: The Past, Present and Future of Our Quest to Go Deeper Underwater

By Jeff Maynard

Triumphs and disasters in the deep sea

This is a journey through time and water, to the bottom of the ocean and the future of our planet.

We do not see the ocean when we look at the water that blankets more than two thirds of our planet. We only see the entrance to it. Beyond that entrance is a world hostile to humans, yet critical to our survival. The first divers to enter that world held their breath and splashed beneath the surface, often clutching rocks to pull them down. Over centuries, they invented wooden diving bells, clumsy diving suits, and unwieldy contraptions in attempts to go deeper and stay longer. But each advance was fraught with danger, as the intruders had to survive the crushing weight of water, or the deadly physiological effects of breathing compressed air. The vertical odyssey continued when explorers squeezed into heavy steel balls dangling on cables, or slung beneath floats filled with flammable gasoline. Plunging into the narrow trenches between the tectonic plates of the Earth’s crust, they eventually reached the bottom of the ocean in the same decade that men first walked on the moon.

Today, as nations scramble to exploit the resources of the ocean floor, The Frontier Below recalls a story of human endeavour that took 2,000 years to travel seven miles, then investigates how we will explore the ocean in the future.

Meticulously researched and drawing extensively on unpublished sources and personal interviews, The Frontier Below is the untold story of the pioneers who had the right stuff, but were forgotten because they went in the wrong direction.

• Language: English
• Publisher: HarperCollins UK
• Release date: Apr 13, 2023
• ISBN: 9780008532741

Jeff Maynard

Jeff Maynard is an experienced author whose books include The Unseen Anzac, Wings of Ice, Niagara’s Gold, and Divers in Time. He has written for television and is a book reviewer for Melbourne’s Herald Sun. A member of the Explorers Club and a former president of the Historical Diving Society, he currently resides in Melbourne, Australia.

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Introduction

One Giant Plunge for Mankind

Whether we fly over it, sail across it, or simply stand on a shore to stare at it, the ocean appears immense. We must remember that what we are seeing is not really the ocean, but merely the entrance to it. When we pass through that entrance, something remarkable happens. The moment water covers our mouth and nostrils, our heart rate slows. It is as if our bodies remember that millions of years ago life began in the ocean, and now if we return to it we will need to conserve oxygen. This response to being submerged is known as the diving reflex, and it is found in all mammals and exhibited strongly in aquatic ones, such as seals, otters and whales. But any welcome that we humans experience in our return to water is short-lived.

If we hold our breath and attempt to swim downward, we feel a force pushing us back to the surface. The Archimedes Principle, supposedly discovered when the Greek mathematician lowered himself into his bath and noticed the water rising as he submerged, says an upward or buoyant force is exerted on a body immersed in fluid equal to the weight of the fluid that the body displaces.

Should we devise a way to overcome our positive buoyancy and continue our descent, we are unable to breathe. Despite our slower heart rate reducing the oxygen supplied to our body cells, we will die in a few minutes when the involuntary action of gasping will fill our larynx with water and deprive our lungs of air. If we attempt to breathe air from the surface through a tube, we immediately discover it is impossible to inhale. Once our bodies are fully submerged the tiny rib muscles are not strong enough to push out against the weight of the water.

When diving, even to 20 ft (6 m), we experience excruciating pain in the ears. The weight of the water pushes on the outside of our eardrums, which are thin flaps of skin, stretched tight, in our ear canals. Unless we somehow relieve the pressure, our eardrums will burst inward, leaving us partially deaf. When this happens, we will be about 33 ft (10 m) underwater and the pressure on our bodies is twice what they are used to. Doubling the pressure on our lungs means they will be compressed to half their usual size. The air in them will be at twice the pressure we normally breathe. That air consists of approximately 20 percent oxygen and 80 percent nitrogen. If we continue to go deeper, breathing compressed nitrogen will have adverse physiological effects on us. Somewhere in the vicinity of 100 ft (30 m) we will begin to experience nitrogen narcosis. It affects our judgement, and unless we return to the surface, we risk hallucinating or doing something irrational, such as attempting to breathe like fish.

Meanwhile our lungs, now under an additional 3 ATM of pressure, have compressed further. If we somehow contrive to breathe compressed air to equalize the weight of the water, the nitrogen in that air will become liquid and be forced into our body tissue. If we stay at 100 ft, this will continue to happen until our body tissue is saturated with nitrogen. If we return to the surface too quickly, the compressed nitrogen, suddenly relieved of the pressure, will bubble out into our bloodstream. The bubbles will congregate in our joints and cripple us, or reach our heart and kill us. All this happens if we manage to reach 100 ft in an ocean with an average depth of 12,000 ft (3.7 km) and is, in places, more than 35,000 ft, or 7 miles (10.7 km), deep.

We can, of course, invent a vessel to protect us from the water pressure and seal ourselves inside it. Knowing, as we do now, that we inhale oxygen and exhale carbon dioxide, we will need to invent a way to supply our bodies with oxygen and remove the carbon dioxide within our sealed vessel. And it will need to be incredibly strong. As we go deeper, the water pressure will increase until, at the bottom of the ocean, our protective shell will have more than seven tons pressing on each square inch of its surface, or more than a metric tonne on each square centimeter. The smallest flaw in our engineering will see the vessel crushed like an egg under the wheel of a truck. Any vessel built to withstand such crushing force will, by design, be extremely heavy. If it is dropped in the ocean, with a person inside, it will have no problem sinking to the bottom. Getting it back to the surface will be another matter.

*

Life began in the ocean and crawled onto the land. It evolved until, around two million years ago, as small almost-human great apes we walked out of Africa. We grew taller, developed larger brains, learned to use tools, and controlled fire. We drew pictures and felt emotion. We learned to protect ourselves from, or kill, larger or more vicious animals. We spoke. We continued walking, or sometimes sailing short distances, until we had circled the globe and populated every continent except Antarctica.

We were attracted back into the water to gather food, please our gods, retrieve items of value, wage war, explore, seek adventure, or to understand the nature of the world beyond the surface of the ocean, which blankets 70 percent of our tiny planet.

Our return to the ocean was not easy. But we are inventive creatures, and just as we learned to leave the earth in hot air balloons, airplanes and rockets, we also learned to survive the lack of breathable air and the crushing weight of water to travel downward, eventually reaching the bottom of the ocean in the same decade as we walked on the Moon.

But only twelve people walked on the Moon between 1969 and 1972, and fifty years elapsed before the cost of the technology had decreased, and the desire to exploit the Moon’s resources had increased to levels where nations felt it worthwhile to return and stake their claims. Exploration is always followed by exploitation, but there is often a gap between the two because the first is driven by passion, which is focused and irrational, while the second carefully weighs costs against benefits.

It is the same with the seabed. The deepest point of the ocean was reached in January 1960. Fifty-two years elapsed before filmmaker James Cameron returned. As I am writing this, the Chinese state-run news agency, Xinhua, is reporting the Chinese Deep Submersible Vehicle Fendouzhe is exploring the bottom of the Mariana Trench. Ye Cong, the chief designer of the manned vehicle, told the news agency that hi-tech diving equipment could help draw a ‘treasure map’ of the bottom of the ocean, which is abundant with resources, in particular the rare earth minerals that are a critical component of computer technology.

The world’s superpowers, along with other states, are developing Autonomous Underwater Vehicles (AUVs), which are fundamentally underwater drones. Many people believe that AUVs are the future of warfare because they are cheap to produce, difficult to detect, and just as drones can replace airplanes to remotely attack enemies from the air, AUVs can replace, or supplement, submarines underwater. Meanwhile, environmentalists are sounding alarms about the depletion of fish stocks, the dangerous levels of plastic in the ocean and the harm caused to underwater ecosystems by rising temperatures. Despite this destruction, economists are predicting the ocean economy (ocean-based industries combined with the assets and resources provided by marine ecosystems) will double in size in the coming decade. There can be no doubt that the ocean is crucial to our survival on this planet, but we can only address the issues that confront it when we think beyond the surface. More than 200 years ago, in ‘Childe Harold’s Pilgrimage’, his poem of a disenchanted young man wandering a devastated world after the Napoleonic Wars, Lord Byron wrote:

Roll on, thou deep and dark blue Ocean, roll!

Ten thousand fleets sweep over thee in vain;

Man marks the earth with ruin; his control

Stops with the shore

Byron was wrong. Our control has never stopped at the shore. But because we cannot easily see past the entrance, we have always taken comfort in expecting that all was well in that world. It isn’t.

So how do we see more? How do we expose our thinking to this critical subject? I contend that appreciating where we are going will be enhanced by understanding where we have been. This book is a record of human exploration downward, from the surface to the bottom of the ocean. With history as our vehicle, I hope you will dive into a new realm of understanding. My primary motive is to entertain and inform with a little-known story of human endeavor. My secondary motive is to stimulate awareness of the future, on a foundation of knowledge of the past.

In an attempt to give the reader a clearer understanding of the vertical journey we are about to take, I have divided this book into four sections, each corresponding with an ocean zone. It is important to realize the diagrams that illustrate the ocean zones in books and websites are misleading. They are invariably drawn out of proportion. The upper Epipelagic Zone is always illustrated larger to accommodate its enormous variety of life. In reality, it is tiny when compared with the other zones.

Therefore, I offer another way to envision the ocean zones. Imagine you are standing with your feet in the deepest part of the ocean and with the top of your head at sea level. As the tide rises and falls, the difference in water level is roughly equivalent to the thickness of two, or perhaps three, strands of your hair.

Now let’s travel down from the surface. We first enter the Epipelagic Zone, which takes its name from the Greek epi, meaning surface, and pelagos meaning sea. The Epipelagic Zone is also known as the Sunlit Zone because sunlight penetrates the water and brings life to photosynthetic plankton, which converts carbon dioxide into energy. The Earth’s rainforests are not, as some people have stated, the ‘lungs of the world’. The Epipelagic Zone is. It produces up to 80 percent of our oxygen. It is also home to 90 percent of ocean life, including the most recognizable forms such as whales, dolphins, fish, sharks and jellyfish.

As we stand in our ocean and continue down, about halfway between the top of our skull and the top of our ears, we leave the Epipelagic Zone and enter the Mesopelagic Zone. This zone, like the others, takes its name from the Greek meso meaning middle. But we are a long way from the middle, or even the average depth of the ocean. The Mesopelagic Zone is sometimes called the Twilight Zone, because the last faint rays of light from a sun high in the sky, are fading by the time they reach the top of this zone. Vertebrates and invertebrates live here in darkness, with many of them swimming upwards at night to feed. Some plant life also survives here.

On our submerged body, somewhere between the bottom of our nose and the top of our mouth, we leave the Mesopelagic Zone and enter the Bathypelagic Zone. Bathy means deep. This zone is in perpetual darkness. No plant life lives here. Some, water-borne organisms are luminescent to attract prey or a mate. Many species here are totally blind, and most live on the detritus that falls from the higher zones.

Just below the bottom of our sternum, before we reach our navel, we enter the Abyssopelagic Zone. Abyss means seemingly bottomless. The water is high in oxygen, but low in nutrients. There is very little discernible life and the water is cold – about 37 °F or 3 °C. Chemosynthetic bacteria thrive near hydrothermal vents in the Abyssopelagic Zone. What fish and invertebrates do live here feed on these bacteria. This, in a sense, is ground zero in the food chain.

To stand in the deepest part of the ocean we need to stand in one of the trenches between the tectonic plates. In our imaginary exercise, we are standing in the Mariana Trench, located off the Mariana Islands in the Pacific Ocean. Trenches are extremely narrow. The one we are standing in, begins at our groin. In the 1950s, scientists began to notice distinct life in the trenches and started referring to them as the Hadal Zone. A Greek derivative again, but whereas the names of the zones above indicate where in the ocean they are located, the Hadal Zone was named to signify what. Welcome to hell.

Let us begin our journey.

Part I

The Epipelagic Zone

Antiquity to 1840

The surface to 200 meters (656 feet)

1

Archimedes’ Bathtub

The first piece of diving equipment was a rock. When early humans tried to swim below the surface of lakes, rivers or coastal waters, they discovered their bodies floated upward, so they learned to grab hold of a rock, take a deep breath, and allow the weight to pull them down. When they could hold their breath no longer, they let go of the rock and felt themselves being pulled to the surface. They understood the need to overcome their positive buoyancy thousands of years before Archimedes articulated his principle. People used rocks to dive to shallow depths, usually to spear fish or collect something edible, but they were not enticed deeper, nor did diving become a profession, until they conceived gods.

By the time sea levels had stopped rising, around 10,000 years ago, many hunter-gatherers had ceased wandering and formed communities in areas that would become cradles of civilization. Making shelters, tending flocks, planting crops, harvesting grain, baking breads and all the tasks of communal living required hierarchical organization. Someone had to herd the animals and someone had to record their number. Someone needed to decide how much grain could be eaten after the harvest and how much should be stored for the winter. Communal life only functioned if there were leaders and followers. Critical to any developing civic system was religious belief. Leaders could only control and console a community if they could explain the inexplicable. Why, for example, did some seasons bring plentiful rains and bountiful crops, while others brought drought and famine? Leaders soon learned to gesture to some inaccessible place and explain that gods lived there. If those gods were pleased, the people would get what they needed and be fed and kept safe. If the people disobeyed the rules of the gods (which were always communicated via their chosen representatives, rather than directly to the people) then the gods would be displeased and the people would suffer.

Gods are invisible. Leaders understood they had to display tangible symbols to prove they had been ordained by the intangible authorities. They needed to live in the largest hut, sit in the highest position, or be adorned with something, such as a crown or an elaborate piece of clothing. In antiquity, throughout Asia and in the civilizations that flourished around the Mediterranean Sea, there were two unquestionable symbols of consecration and power – gold and pearls. While ancient people dug for gold, they dove for pearls. Therefore, it was pearls, and pearl shell, that first lured people to go deeper and attempt to stay longer underwater.

Pearls are a gem perfected by nature. They don’t need to be polished like stones or beaten into shapes like gold. While almost all mollusks are capable of producing pearls, certain varieties of pinctada (pearl oyster), a type of saltwater clam, occasionally produce round, or nearly round, pearls of extraordinary translucence and beauty, while the smooth shiny inner layer of the shell itself (mother-of-pearl) can be carved to make ornamental jewelry and practical tools. The richest pearl beds of antiquity were located between Sri Lanka (formerly Ceylon) and India, and in the Persian Gulf. Other pearl fisheries existed in the Red Sea, the Gulf of Aden, the Gulf of Mexico, Panama, Japan, Korea and Thailand. [fn1]

The Vedas, the body of religious texts originating in ancient India, allude to pearl decorations more than a millennium before the Christian era. The two ancient Indian epic poems, ‘Ramayana’ and ‘Mahabharata’, believed to pre-date 400 BCE, mention pearls and pearl necklaces. Pearls are often mentioned in the ancient literature of Hinduism. Krishna, perhaps the most popular Hindu incarnation of the deity, Lord Vishnu, is frequently associated with pearls. Likewise, ancient books from China have numerous references to pearls. One of the earliest, the Shujing (sometimes Shu King), dating from around 2350 to 625 BCE, notes that in the twenty-third century BCE, strings of pearls were offered as tributes. In the ancient records of countries around the Persian Gulf, pearls are also mentioned as tributes of adornment. Portraits of Persian queens show pearl ear pendants. In Egypt, mother-of-pearl was fashioned into ornaments as early as the Sixth Dynasty (c.3200 BCE). The art-loving ancient Greeks had a high estimation of pearls, which they probably obtained from the Phoenicians. The Greek love of luster was inherited by the Roman Empire, where Julius Caesar forbade women below a certain rank to wear pearls and, later, Caligula declared his horse a consul and gave it a pearl necklace.

Old Testament references to certain stones may refer to pearls. Certainly, by the time of the New Testament, their importance was established. Jesus used them in his analogies, saying (in Matthew 13:45–46), ‘Again, the kingdom of heaven is like a merchant looking for fine pearls. When he found one of great value, he went away and sold everything he had and bought it.’ In Matthew 7:6, he again emphasizes the value of pearls by saying, during the Sermon on the Mount, ‘Do not give dogs what is sacred; do not throw your pearls before swine.’ The Book of Revelations, written fifty to seventy years after the death of Jesus, claimed the twelve gates of heaven were twelve pearls. Hence, the devout Christian enters heaven through the Pearly Gates. The Koran’s description of Paradise has pearls as stones on the ground and as the fruit of trees.

By the time people had begun to record their history, art and beliefs, pearls were established as objects of beauty, wealth, power and divinity. But while the ancient texts spoke of the value of pearls and praised those who owned them, nothing is recorded about the people who collected them.

We need to wait until visitors to the centers of the pearling industry recorded descriptions of the divers who trained their bodies and risked their lives to collect pearl shell. In 1508 CE, Ludovico di Varthema, the Italian traveller, diarist and aristocrat, visited the Island of Ormus, the center of the pearling industry in the Persian Gulf, and described the divers:

There are certain fishermen who go there in small boats, and cast into the water two large stones attached to ropes, one at the bow, the other at the stern of each boat to stay in place. Then one of the fishermen hangs a sack from his neck, attaches a large stone to his feet, and descends to the bottom – about fifteen paces underwater, [fn2] where he remains as long as he can, searching for oysters which bear pearls, and puts as many as he finds in his sack. When he can remain no longer, he casts off the stone attached to his feet, and ascends by one of the ropes attached to the boat.

There are so many connected with the business that you will often see 300 of these little boats which come from many countries. [1]

Other observers noted that the divers wore only a loin cloth, or sometimes light cotton clothing for protection from scratches. Some also wore leather gloves to protect their fingers as they clawed at the shells to dislodge them. Kunz and Stevenson, in their exhaustively researched study, The Book of the Pearl, wrote:

The diving stones range in weight from thirty to fifty pounds [14 kg–23 kg] each, depending largely on the depth of the water and the weight of the fisherman. They are somewhat oval in shape, and have one end perforated to admit a rope. Immediately above the attachment is formed a loop, resembling a stirrup to receive the diver’s foot. When prepared for the day’s work, each stone is suspended by a stout rope over outriggers projecting from the side of the boat, and by a slip-knot is temporarily held four and a half or five feet below the surface of the water. A very stout diver may have a stone affixed to overcome his greater buoyancy. Usually two divers use one stone together and descend alternatively. Each one has an attendant in the boat who assists him in ascending, and looks after the ropes, baskets of shells, etc. [2]

On the surface, while one diver sucked in air and another prepared to descend, an attendant in the boat emptied the contents of the basket. That attendant sorted through the haul and threw the rubbish overboard, while another pulled up the diving stone, so the resting diver could prepare to go down. In this manner, each diver could manage thirty to forty dives in a working day. The number of shells collected per dive depended on their abundance on the bottom, as well as the depth and clarity of the water. Ten shells was outstanding. Sometimes the divers worked for a share of the shells they collected, so each diver’s haul was kept separate on the boat.

Pearl divers would train their bodies from a young age. Children often followed a parent into the industry. Their eardrums would burst. They learned to relax their breathing and be pulled down by a diving stone. With experience they learned to control the urge to take a breath and they knew to let go of the stone if they felt themselves blacking out.

There are fanciful stories told by travellers to the Persian Gulf, India and Sri Lanka, of divers staying down for three or four minutes. Other stories are even more implausible. Ibn Battúta, the Moroccan scholar and traveller in the fourteenth century, wrote that ‘some of them being able to stay under for an hour or two hours or less’. [3]

An earlier writer, Jouchanan ibn Masouiah, from the ninth century had divers staying down half an hour. In reality, a fit diver, thrashing about at a depth of thirty feet could stay underwater for about sixty seconds. It is possible for people to hold their breath, or stay underwater for longer, but they are usually in a resting state.

Aside from pearl shells, divers of antiquity plunged underwater to gather red coral and sponges. Red coral, which is fashioned into jewelry, is found throughout the Mediterranean, while sponge diving was concentrated towards the eastern end, particularly around the Greek islands. [fn3]

Often thought to be plants, sea sponges are in fact an underwater animal. They branched off from the evolutionary tree when it was still a sapling and never developed a nervous, digestive or circulatory system. Instead they rely on a constant flow of warm water through their bodies to supply them with food and oxygen, and to remove waste. While there are many species of sponges, the best commercial varieties live in water that remains above 55 °F (13 °C). While pearls and corals were prized for their beauty, sponges had more practical applications. Their ability to absorb and hold water, then have it squeezed out, made them ideal for washing tables and utensils, or for personal hygiene. The ancient Romans put sponges on a stick, which they would dip in vinegar to wipe their anuses after going to the toilet.

Unlike the divers who grabbed any pearl shell they saw on the seabed, sponge divers had to exercise time-consuming discretion. As they swam, fighting the urge to gulp in air that wasn’t there, they needed to distinguish between useful varieties of sponges and wild varieties that had no commercial value. Underwater, both were black, or a dark grey/black, but the wild varieties which have a shiny surface cannot be made soft. Commercial sponges have a dull exterior. The diver would scrape at the surface of a potential prize with his knife, hoping for a skin that peeled off easily. If the sponge was suitable, the diver would cut it free, and carry it to the surface, where it would be brought on board the dive boat. The crew would stomp on the sponge to kill any organisms in the pores and squeeze out a white milky substance. The sponges would then be washed, usually by putting them in a net and lowering them back into the sea, before they were finally strung up to dry.

So sponge diving, like pearl diving, remained unchanged in some areas until the late nineteenth century. Diving equipment for gathering pearl shells, decorative corals, or sponges, consisted of rocks, ropes and near-bursting lungs.

*

Once ancient communities had settled an area, learned to feed themselves, accepted their leaders and imagined their gods, their next concern was war. They attacked other communities, or defended themselves from being attacked. War gave people another reason to swim underwater – concealment.

An Assyrian bas-relief, held in the British Museum, shows an incident, thought to have occurred in 878 BCE, which may show swimmers attempting to breathe from inflated animal skins. The Assyrian King, Ashurnasirpal II, who was expanding his empire, had embarked on a campaign of conquest down the Euphrates River and had reached an enemy city somewhere near present-day Anah. The relief shows the attack on the fortified city by the Assyrian soldiers, who are depicted in detail with their pointed helmets, bows, arrows, quivers and swords. The enemy is also depicted and care is taken with the details of their features. Interestingly, beneath the surface of the Euphrates, three swimmers are approaching the fort. Two of them appear to be holding inflated animal skins (perhaps goat skins) beneath their chests and each has a section of the skin – the leg of the animal – in their mouth. Whether they are blowing air into the skins to use them as flotation devices, or are attempting to suck air from them, cannot be determined, but it is an early depiction of divers employing something other than rocks.

While Ashurnasirpal II, and other Assyrian leaders (soon to be overtaken by the Persian Empire) were spreading their influence, the Greeks were developing an alphabet that allowed them to articulate and record thought. During the Greek Classical Period (c.500–300 BCE) ideas, history, instructions and laws were written down. It is from this period that we begin to get descriptions, both real and fanciful, of attempts to breathe underwater. Early divers made snorkels by breathing through hollow reeds. They discovered (although they probably didn’t understand why) they could not draw air into their lungs once their body was submerged. There are records of Greek sponge divers attempting to get an extra breath of air by sucking a dry sponge held by their teeth.

Both snorkels and sponges may have seemed logical to a thinker sitting on dry land breathing air at 1 ATM. But they could not conceive the weight of the water that would stop the chest expanding to draw air through the snorkel. Nor would they have understood the purpose of the lungs, or that the average adult male lung capacity is approximately 1.6 US gallons (6 liters). Any small amount of air not squeezed out of the sponge by the water would have been completely inadequate to supply them sufficient oxygen had they somehow managed to inhale it.

A description of divers comes from Herodotus (c.484–425 BCE), who is acknowledged as the Father of History because he gathered facts and recorded them in chronological order. Herodotus wrote about the Greco–Persian Wars, as the developing Greek city-states coordinated a pushback against the Persians encroaching from the east.

In 480 BCE, the Persian King, Xerxes, after spending three years building a massive fleet of ships and an enormous army, attempted to invade Greece. Xerxes dispatched 200 ships to divert some of the Greek forces south, while his main force attacked farther north. On board one of the Persian ships, which was among the diversionary force, was a Greek diver, Scyllias and his daughter Hydna. (Scyllias had possibly been a sponge diver and taught his daughter to swim and dive from an early age.) Father and daughter had been previously hired by the Persians to recover property from sunken ships. Both now wanted to be free of their masters and return to Greece, but the Persians held them captive to prevent them revealing Xerxes’ plans. While the 200 ships were laying at anchor in a sheltered bay, waiting for a storm to pass before commencing their attack, Scyllias and Hydna slipped overboard and swam between the ships, quietly cutting as many anchor ropes as possible, before making their escape. Still enduring the storm, the ships crashed into one another. Some were damaged and others sank. While the Persian fleet was trapped in the congested harbor, a smaller Greek fleet attacked and destroyed it in the Battle of Salamis.

Herodotus, recording his history of the wars (he was an infant when the Battle of Salamis took place) marvelled at the swimming exploits of Scyllias and Hydna, saying, ‘It is said they dived into the Aphetae [an ancient port in the Pagasetic Gulf] and did not come to the surface until they reached Artemisium.’ [4] To do so, Scyllias and Hydna must have swum approximately ten miles, which is possible, but unlikely.

By the time Herodotus recorded the story, the legend of Scyllias and Hydna was already larger-than-life and they were remembered as the divers who saved western civilization. The legend was probably fuelled by the pride the Greeks already had in their sponge divers. Statues