by Bill Bryson
As in all zones of the earthly realm, life in the oceans is mostly microscopic. The colour-enhanced specimens shown here, tiny protozoans known as radiolarians, were first described in the late 1800s by the German naturalist Ernst Haeckel on the basis of specimens gathered on research cruises of HMS Challenger. (credit 18.1)
THE BOUNDING MAIN
Imagine trying to live in a world dominated by dihydrogen oxide, a compound that has no taste or smell and is so variable in its properties that it is generally benign but at other times swiftly lethal. Depending on its state, it can scald you or freeze you. In the presence of certain organic molecules it can form carbonic acids so nasty that they can strip the leaves from trees and eat the faces off statuary. In bulk, when agitated, it can strike with a fury that no human edifice could withstand. Even for those who have learned to live with it, it is an often murderous substance. We call it water.
Water is everywhere. A potato is 80 per cent water, a cow 74 per cent, a bacterium 75 per cent. A tomato, at 95 per cent, is little but water. Even humans are 65 per cent water, making us more liquid than solid by a margin of almost two to one. Water is strange stuff. It is formless and transparent, and yet we long to be beside it. It has no taste and yet we love the taste of it. We will travel great distances and pay small fortunes to see it in sunshine. And even though we know it is dangerous and drowns tens of thousands of people every year, we can’t wait to frolic in it.
Because water is so ubiquitous we tend to overlook what an extraordinary substance it is. Almost nothing about it can be used to make reliable predictions about the properties of other liquids, and vice versa. If you knew nothing of water and based your assumptions on the behaviour of compounds most chemically akin to it—hydrogen selenide or hydrogen sulphide, notably—you would expect it to boil at minus 93 degrees Celsius and to be a gas at room temperature.
Most liquids when chilled contract by about 10 per cent. Water does too, but only down to a point. Once it is within whispering distance of freezing, it begins—perversely, beguilingly, extremely improbably—to expand. By the time it is solid, it is almost a tenth more voluminous than it was before. Because it expands, ice floats on water—“an utterly bizarre property,” according to John Gribbin. If it lacked this splendid waywardness, ice would sink, and lakes and oceans would freeze from the bottom up. Without surface ice to hold heat in, the water’s warmth would radiate away, leaving it even chillier and creating yet more ice. Soon even the oceans would freeze and almost certainly stay that way for a very long time, probably for ever—hardly the conditions to nurture life. Thankfully for us, water seems unaware of the rules of chemistry or laws of physics.
Everyone knows that water’s chemical formula is H2O, which means that it consists of one largish oxygen atom with two smaller hydrogen atoms attached to it. The hydrogen atoms cling fiercely to their oxygen host, but also make casual bonds with other water molecules. The nature of a water molecule means that it engages in a kind of dance with other water molecules, briefly pairing and then moving on, like the ever-changing partners in a quadrille, to use Robert Kunzig’s nice phrase. A glass of water may not appear terribly lively, but every molecule in it is changing partners billions of times a second. That’s why water molecules stick together to form bodies like puddles and lakes, but not so tightly that they can’t be easily separated as when, for instance, you dive into a pool of them. At any given moment only 15 per cent of them are actually touching.
In one sense the bond is very strong—it is why water molecules can flow uphill when siphoned and why water droplets on a car bonnet show such a singular determination to bead with their partners. It is also why water has surface tension. The molecules at the surface are attracted more powerfully to the like molecules beneath and beside them than to the air molecules above. This creates a sort of membrane strong enough to support insects and skipping stones. It is what gives the sting to a belly-flop.
Surface tension of water, shown here by floating dandelion seeds, results because the molecules on the surface of water are more powerfully attracted to other water molecules than to the air above them. (credit 18.2)
I hardly need point out that we would be lost without it. Deprived of water, the human body rapidly falls apart. Within days, the lips vanish “as if amputated, the gums blacken, the nose withers to half its length, and the skin so contracts around the eyes as to prevent blinking,” according to one account. Water is so vital to us that it is easy to overlook that all but the smallest fraction of the water on Earth is poisonous to us—deadly poisonous—because of the salts within it.
We need salt to live, but only in very small amounts, and sea water contains way more—about seventy times more—salt than we can safely metabolize. A typical litre of sea water will contain only about 2.5 teaspoons of common salt—the kind we sprinkle on food—but much larger amounts of other elements, compounds and other dissolved solids, which are collectively known as salts. The proportions of these salts and minerals in our tissues are uncannily similar to those in sea water—we sweat and cry sea water, as Margulis and Sagan have put it—but curiously we cannot tolerate them as an input. Take a lot of salt into your body and your metabolism very quickly goes into crisis. From every cell, water molecules rush off like so many volunteer firemen to try to dilute and carry off the sudden intake of salt. This leaves the cells dangerously short of the water they need to carry out their normal functions. They become, in a word, dehydrated. In extreme situations, dehydration will lead to seizures, unconsciousness and brain damage. Meanwhile, the overworked blood cells carry the salt to the kidneys, which eventually become overwhelmed and shut down. Without functioning kidneys you die. That is why we don’t drink sea water.
There are 1.3 billion cubic kilometres of water on Earth and that is all we’re ever going to get. The system is closed: practically speaking, nothing can be added or subtracted. The water you drink has been around doing its job since the Earth was young. By 3.8 billion years ago, the oceans had (at least more or less) achieved their present volumes.
The water realm is known as the hydrosphere and it is overwhelmingly oceanic. Ninety-seven per cent of all the water on Earth is in the seas, the greater part of it in the Pacific, which is bigger than all the land masses put together. Altogether the Pacific holds just over half of all the ocean water (51.6 per cent); the Atlantic has 23.6 per cent and the Indian Ocean 21.2 per cent, leaving just 3.6 per cent to be accounted for by all the other seas. The average depth of the ocean is 3.86 kilometres, with the Pacific on average about 300 metres deeper than the Atlantic and Indian Oceans. Sixty per cent of the planet’s surface is ocean more than 1.6 kilometres deep. As Philip Ball notes, we would better call our planet not Earth but Water.
Of the 3 per cent of Earth’s water that is fresh, most exists as ice sheets. Only the tiniest amount—0.036 per cent—is found in lakes, rivers and reservoirs, and an even smaller part—just 0.001 per cent—exists in clouds or as vapour. Nearly 90 per cent of the planet’s ice is in Antarctica and most of the rest is in Greenland. Go to the South Pole and you will be standing on over 2 miles of ice, at the North Pole just 15 feet of it. Antarctica alone has 6 million cubic miles of ice—enough to raise the oceans by a height of 200 feet if it all melted. But if all the water in the atmosphere fell as rain, evenly everywhere, the oceans would deepen by only a couple of centimetres.
Sea level, incidentally, is an almost entirely notional concept. Seas are not level at all. Tides, winds, the Coriolis force and other effects alter water levels considerably from one ocean to another and even within oceans. The Pacific is about a foot and a half higher along its western edge—a consequence of the centrifugal force created by the Earth’s spin. Just as when you pull on a tub of water the water tends to flow towards the other end, as if reluctant to come with you, so the eastward spin of Earth piles water up against the ocean’s western margins.
Considering the age-old importance of the seas to us, it is striking how long it took the worl
d to take a scientific interest in them. Until well into the nineteenth century most of what was known about the oceans was based on what washed ashore or came up in fishing nets, and nearly all that was written was based more on anecdote and supposition than on physical evidence. In the 1830s, the British naturalist Edward Forbes surveyed ocean beds throughout the Atlantic and Mediterranean and declared that there was no life at all in the seas below 600 metres. It seemed a reasonable assumption. There was no light at that depth, so no plant life, and the pressures of water at such depths were known to be extreme. So it came as something of a surprise when, in 1860, one of the first transatlantic telegraph cables was hauled up for repairs from more than 3 kilometres down and found to be thickly encrusted with corals, clams and other living detritus.
The first really organized investigation of the seas didn’t come until 1872, when a joint expedition set up by the British Museum, the Royal Society and the British government set forth from Portsmouth on a former warship called HMS Challenger. For three and a half years they sailed the world, sampling waters, netting fish and hauling a dredge through sediments. It was evidently dreary work. Out of a complement of 240 scientists and crew, one in four jumped ship and eight more died or went mad—“driven to distraction by the mind-numbing routine of years of dredging,” in the words of the historian Samantha Weinberg. But they sailed across almost 70,000 nautical miles of sea, collected over 4,700 new species of marine organisms, gathered enough information to create a fifty-volume report (which took nineteen years to put together), and gave the world the name of a new scientific discipline: oceanography. They also discovered, by means of depth measurements, that there appeared to be submerged mountains in mid-Atlantic, prompting some excited observers to speculate that they had found the lost continent of Atlantis.
The first page of the journal of Pelham Aldrich, who set out on HMS Challenger in 1872 to scour the world’s oceans for new types of life. The expedition found 4,700 previously unknown species and gave birth to the new science of oceanography. (credit 18.3)
Because the institutional world mostly ignored the seas, it fell to devoted —and very occasional—amateurs to tell us what was down there. Modern deep-water exploration begins with Charles William Beebe and Otis Barton in 1930. Although they were equal partners, the more colourful Beebe has always received far more written attention. Born in 1877 into a well-to-do family in New York City, Beebe studied zoology at Columbia University, then took a job as a birdkeeper at the New York Zoological Society. Tiring of that, he decided to adopt the life of an adventurer and for the next quarter-century travelled extensively through Asia and South America with a succession of attractive female assistants whose jobs were inventively described as “historian and technicist” or “assistant in fish problems.” He supported these endeavours with a succession of popular books with titles like Edge of the Jungle and Jungle Days, though he also produced some respectable books on wildlife and ornithology.
In the mid-1920s, on a trip to the Galápagos Islands, he discovered “the delights of dangling,” as he described deep-sea diving. Soon afterwards he teamed up with Barton, who came from an even wealthier family, had also attended Columbia and also longed for adventure. Although Beebe nearly always gets the credit, it was in fact Barton who designed the first bathysphere (from the Greek word for “deep”) and funded the $12,000 cost of its construction. It was a tiny and necessarily robust chamber, made of cast iron 1.5 inches thick and with two small portholes containing quartz blocks 3 inches thick. It held two men, but only if they were prepared to become extremely well acquainted. Even by the standards of the age, the technology was unsophisticated. The sphere had no manoeuvrability—it simply hung on the end of a long cable—and only the most primitive breathing system: to neutralize their own carbon dioxide they set out open cans of soda lime, and to absorb moisture they opened a small tub of calcium chloride, over which they sometimes waved palm fronds to encourage chemical reactions.
But the nameless little bathysphere did the job it was intended to do. On the first dive, in June 1930 in the Bahamas, Barton and Beebe set a world record by descending to 183 metres. By 1934, they had pushed the record to over 900 metres, where it would stay until after the Second World War. Barton was confident the device was safe to a depth of about 1,400 metres, though the strain on every bolt and rivet was audibly evident with every fathom they descended. At any depth, it was brave and risky work. At 900 metres, their little porthole was subjected to 19 tons of pressure per square inch. Should they pass the structure’s limits of tolerance, death at such a depth would have been instantaneous, as Beebe never failed to observe in his many books, articles and radio broadcasts. Their main concern, however, was that the shipboard winch, straining to hold onto a metal ball and two tons of steel cable, would snap and send the two men plunging to the sea floor. In such an event, nothing could have saved them.
Charles William Beebe (left) and Otis Barton with the nameless and sometimes worryingly leaky bathysphere in which they made record-breaking descents throughout the 1930s. (credit 18.4)
The one thing their descents didn’t produce was a great deal of worthwhile science. Although they encountered many creatures that had not been seen before, the limits of visibility and the fact that neither of the intrepid aquanauts was a trained oceanographer meant they often weren’t able to describe their findings in the kind of detail that real scientists craved. The sphere didn’t carry an external light, merely a 250-watt bulb they could hold up to the window, but the water below 150 metres was practically impenetrable anyway, and they were peering into it through three inches of quartz, so anything they hoped to view would have to be nearly as interested in them as they were in it. About all they could report, in consequence, was that there were a lot of strange things down there. On one dive in 1934, Beebe was startled to spy a giant serpent “more than twenty feet long and very wide.” It passed too swiftly to be more than a shadow. Whatever it was, nothing like it has been seen by anyone since. Because of such vagueness, their reports were generally ignored by academics.
A painting of the minuscule but terrifying sabre-toothed viperfish, based on Barton and Beebe’s observations from their bathysphere. (credit 18.5)
After their record-breaking descent of 1934, Beebe lost interest in diving and moved on to other adventures, but Barton persevered. To his credit, Beebe always told anyone who asked that Barton was the real brains behind the enterprise, but Barton seemed unable to step from the shadows. He, too, wrote thrilling accounts of their underwater adventures and even starred in a Hollywood movie called Titans of the Deep, featuring a bathysphere and many exciting and largely fictionalized encounters with aggressive giant squid and the like. He even advertised Camel cigarettes (“They don’t give me jittery nerves”). In 1948 he increased the depth record by 50 per cent, with a dive to 1,370 metres in the Pacific Ocean near California, but the world seemed determined to overlook him. One newspaper reviewer of Titans of the Deep actually thought the star of the film was Beebe. Nowadays, Barton is lucky to get a mention.
At all events, he was about to be comprehensively eclipsed by a father and son team from Switzerland, Auguste and Jacques Piccard, who were designing a new type of probe called a bathyscaphe (meaning “deep boat”). Christened Trieste, after the Italian city in which it was built, the new device manoeuvred independently, though it did little more than just go up and down. On one of its early dives, in early 1954, it descended to below 4,000 metres, nearly three times Barton’s record-breaking dive of six years earlier. But deep-sea dives required a great deal of costly support and the Piccards were gradually going broke.
In 1958, they did a deal with the US Navy which gave the Navy ownership but left them in control. Now flush with funds, the Piccards rebuilt the vessel, giving it walls nearly 13 centimetres thick and shrinking the windows to just 5 centimetres in diameter—little more than peepholes. But it was now strong enough to withstand truly enormous pressures, and in January 1960 Jacques P
iccard and Lt. Don Walsh of the US Navy sank slowly to the bottom of the ocean’s deepest canyon, the Mariana Trench, some 400 kilometres off Guam in the western Pacific (and discovered, not incidentally, by Harry Hess with his fathometer). It took just under four hours to fall 10,918 metres, or almost 7 miles. Although the pressure at that depth was nearly 17,000 pounds per square inch, they noticed with surprise that they disturbed a bottom-dwelling flatfish just as they touched down. They had no facilities for taking photographs, so there is no visual record of the event.
Auguste Piccard, whose bathyscaphe Trieste made the deepest descent ever undertaken in 1960. (credit 18.6)
After just twenty minutes at the world’s deepest point, they returned to the surface. It was the only occasion in which human beings have gone so deep.
Forty years later, the question that naturally occurs is: why has no-one gone back since? To begin with, further dives were vigorously opposed by Vice Admiral Hyman G. Rickover, a man with a lively temperament, forceful views and, most pertinently, control of the departmental chequebook. He thought underwater exploration a waste of resources and pointed out that the Navy was not a research institute. The nation, moreover, was about to become fully preoccupied with space travel and the quest to send a man to the Moon, which made deep sea investigations seem unimportant and rather old-fashioned. But the decisive consideration is that the Trieste descent didn’t actually achieve much. As a navy official explained years later: “We didn’t learn a hell of a lot from it, other than that we could do it. Why do it again?” It was, in short, a long way to go to find a flatfish, and expensive too. Repeating the exercise today, it has been estimated, would cost at least $100 million.