Ninety per cent of the world’s oceans remain unexplored, fuelling our fascination for and fear of the sea for centuries, even as we have discovered more of its contents. Artists and writers have explored its complex hold on the human psyche, and Aquatopia takes us on a trans-historical voyage of the oceanic imaginary through the eyes of a fabulously diverse range of artists, including J.M.W. Turner, Odilon Redon, Hokusai, William Wyllie, John Bellany, The Otolith Group and Steven Claydon

For most of human history, the depths of the sea, like the depths of the mind, have remained largely unexplored. Under capitalism the ocean has functioned, in Philip Steinberg’s words, as an ‘empty transportation surface, beyond the space of social relations’; a non-place, the way to somewhere else. Challenges to such an understanding have historically led to conflict, even war. The freedom to travel anywhere in order to annex new territories and trade with (or in) their inhabitants has been, and remains, of paramount importance to Western nations, especially if they happen to be based on an island. As early as 1776, Adam Smith pointed out that ‘a nation of shopkeepers’ would need to build an extensive empire to guarantee itself a sufficiency of customers. At the same time, the shopkeepers themselves would need to eat.

This mercantile view of the sea, as a web of connections and business opportunities to be defended at all costs, masks the far more complex range of relationships human beings have always had with the ocean, just as the scurrying craft on its surface hang above vast, uncharted depths. An active and densely populated region, the deep sea comprises, by volume, 78.5 per cent of the entire habitat of the planet. Literally below the level of our attention, it acts as the world’s unconscious, invisible yet holding sway over our daily lives in ways we are just beginning to understand. Only someone free of the loyalties imposed on surface-dwellers, such as Jules Verne’s stateless Captain Nemo, is equipped through a combination of alienation and genius to navigate its hidden kingdoms. Verne was merely one of many writers, artists and film-makers to populate the deep with a mixture of the latest scientific discoveries and his own creations. Human beings appear to need unknown regions on to which they can project their imaginings. Unlike outer space, that alternate kingdom of exploration for science-fiction writers, the sea is both ‘other’ and something that surrounds us. The briefest swim of a few hundred yards from the shore, as we sense solidity fall away beneath our feet, connects us with subterranean worlds and distant oceans.

Ignoring the unseen is always perilous. Periodically, the denizens of the deep explode upward: vast squid engulf ships; amorous octopi entrap fishermen’s wives; giant sharks and albino whales take revenge on their pursuers; leviathans directed by divine purpose swallow errant prophets whole. Such creatures populate the margins of the atlases that became the best-sellers of the late sixteenth century, entering the public imagination as fact, along with whole continents that did not exist.

Yet more threatening than the sea’s inhabitants is the vastness of the ocean itself. Measured against it, human life and achievements are suddenly seen through the wrong end of Galileo’s telescope, humbled and brought to scale. There are few more chilling phrases in the English language than ‘lost at sea’. On the other hand, some things we wish to lose, in the hope they will never return to haunt us. When Osama bin Laden was finally run to ground and killed in Pakistan in 2011, the decision was taken that his body could not be buried on land in case its location became a place of pilgrimage. Instead, it was flown by helicopter to the USS Carl Vinson aircraft carrier, from which, we are told, prepared for burial according to Islamic practice and wrapped in a white sheet, ‘it slid into the sea’. Any hope that bin Laden’s ideas would sink with his body appears premature; like buried memories or repressed emotions, they keep rising to the surface.

Far from land, land-bound morals and ethics fade. The sea, as we have heard, is viewed as ‘beyond social relations’. This must be why trawlers from developed nations feel it acceptable to plunder the fish of those unable to defend themselves and discharge their toxic waste in tropical waters. The fishing grounds off the coast of West Africa have the largest number of illegal fishing boats of any area of the world: 90 per cent of them are equipped with bottom-trawling equipment that permanently destroys the marine habitat. It is no coincidence that these waters also have such high rates of piracy – denied their livelihoods in one way, local fishermen are forced to make it in another.

The sea’s distancing effect on the morals of home has a micro as well as a macro application. In June 2013 the Royal Navy announced that because of the changing make-up of the armed forces, it would be revising its long-standing officer’s toast on a Saturday night. ‘To our wives and sweethearts!’ the toastmaster has traditionally said, to which the response has been: ‘May they never meet!’ – the custom giving semi-official recognition of the polygamous life of the sailor with ‘a wife in every port’. On board, in the absence of wider social structures, the commander of a vessel assumes the powers of sheriff, judge and priest. Today, this means authorisation to conduct weddings and funerals; historically, it would have included the meting out of justice: courts martial, floggings, imprisonment and execution. Those who, for whatever reason, no longer served a use to the floating kingdom of a ship might expect to leave it over the side.

There is a much-quoted but probably unscientific claim that the migration routes of sharks were permanently altered by the practice of dumping the bodies of dead or dying slaves overboard during the Atlantic passage. The vehemence with which these assertions are denied in comment spaces on the internet surely misses the point. Many thousands would certainly have died during the crossing, while life for those who survived was scarcely better. The reverberations of this legacy have not faded from human consciousness, whether or not they persist in that of the shark.

African-American music, that great storehouse of techniques for coping with the vagaries of life, has a tradition of creating alternate mythologies for a people whose individual histories have been stolen. Sun Ra asserted he was of ‘the angel race’ and that he and his Arkestra came from the planet Saturn; George Clinton claimed his groups Parliament and Funkadelic were ‘certified Afronauts, capable of funkitizing galaxies’. Detroit electronic musicians Drexciya, on the other hand, traced their origins to the deep, rather than outer space. Drexciya, they explained, from behind their mask of anonymity, was an underwater country, populated with the unborn descendants of pregnant slaves thrown overboard. Mutated, amphibious, both timeless and futuristic, these beings could no more be buried and forgotten at sea than black people could be buried and forgotten in the ghettoes of the city.

Perhaps it is fitting that the term unconscious was first coined in English by Samuel Taylor Coleridge, the author of The Rime of the Ancient Mariner. The poem is, of course, an account of the retribution taken by a sub-oceanic spirit on a seaman who has transgressed the law of the sea by killing an albatross. Framed though it is in the traditional language of sin and redemption, it can also be read as a story of the mariner’s mental breakdown after an overwhelming crisis event and his eventual regaining of equilibrium. Outer stasis, in which he is becalmed upon a rotting ocean while slowly dying of thirst, surrounded by his dead companions, is broken when he turns from introspection and contemplates the sea-snakes that writhe around the ship:

Blue, glossy green, and velvet black,
They coiled and swam; and every track
Was a flash of golden fire…

Their beauty provokes ‘a spring of love’ to gush from his heart, and the dead albatross that has been placed around his neck falls like a lead weight into the ocean, a curse sent back to its source. A return of the mental agony he felt on board is avoided only by periodic recounting of his tale, a Romantic precursor of the psychoanalyst’s talking cure.

The sea has always been a place where people have been brought face to face with themselves. It has also always offered an escape from the quotidian. Arthur Cravan, the flamboyant Dadaist poet and erstwhile boxer and nephew of Oscar Wilde, said that he could feel at home only ‘in voyage; when I stay for a long time in the same place, stupidity overwhelms me’. He went missing in a small boat in the Pacific off the coast of Mexico in 1918, en route to Argentina, where he planned to rendezvous with his wife, the poet Mina Loy. News of his disappearance was met with scepticism; Cravan was a self-publicist and adventurer who few could envisage remaining long in a conventional domestic arrangement. A similar scepticism initially surrounded the discovery of the wreckage of the 12 ft dinghy in which the artist Bas Jan Ader attempted to cross the Atlantic in 1975, not least because a copy of The Strange Last Voyage of Donald Crowhurst was found among his effects. The journey itself was a performance, the concluding part of a three-part work entitled Searching for the Miraculous. Had Ader, an artist with a tragic family history whose œuvre is shot through with melancholy, taken his own life? Or had he arranged his disappearance as the perfect artwork? The ultimate precursor for such enigmatic exits is the death in 1822 of the poet Shelley as he sailed in his own boat between Livorno and Lerici on the Italian coast. Rumours circulated that he had been rammed by another vessel in a political assassination or attempted robbery; that he was too unworldly to be a competent sailor; that, as his drowned body burned on a pyre on the shore, a friend snatched his heart.

The sea replaces the rigidities of the terrestrial world with questions and uncertainties, ushering some to oblivion and cloaking others in Romantic myth. For land-dwellers it seems, that other world without air, so closely adjoining ours, leaves room for the imagination to breathe.

James Attlee is the author of Nocturn: A Journey in Search of Moonlight, published by Penguin, and is ‘Writer on the Train’ for First Great Western