Laura Trethewey charts the fascinating history and pursuit of mapping the ocean floor
Review by Mark Rowe
We know more about the surface of the Moon than we do about our own ocean’s floor. Plotting all of the seabed that has been charted onto a map of the world is like plonking a matchbox on your kitchen floor. Yet this is only half the story, as Laura Trethewey’s fascinating and engrossing book reveals. That matchbox, it turns out, has been assembled over centuries of extraordinary exploration from a combination of heroic ventures into the unknown, soothsaying, social history and, most recently, the egos of vastly wealthy, usually white, male entrepreneurs.
The Deepest Map charts the historical and contemporary pursuit of mapping the ocean floor and interjects key technological and political developments between chapters that chart the drama of the Five Deeps, an attempt by one man to dive solo to the deepest point of all five oceans, and of Seabed 2030, a long-term project to map the entire ocean floor by the end of this decade.
It turns out that there simply isn’t enough government money to pay for the seabed to be mapped, so scientists are obligated to make Faustian pacts with larger-than-life billionaire entrepreneurs. Trethewey skilfully captures this oddly symbiotic relationship. Rather than focus on the Alpha Male, the author is just as fascinated by those who, literally, get edited out of the photographs. These include a talented but modest young sleep-deprived mapper who realises belatedly that her job is essentially to ensure her employer’s achievements are copper-bottomed: to chart the seabed accurately enough to validate claims of making it to the depths.
Another is Marie Tharp, who overcame institutional sexism to draft maps in a physiographic style that showed the seabed at an oblique angle, as it might look if you flew over a mountain range. On her maps, the water is drained away and the seabed looks like a space in which you might go for a stroll – the shallow South China Sea, warm and inviting, a good place for a summer holiday. She also used her maps to champion the idea, contentious at the time, of continental drift.
Trying from the ocean surface to calculate the depth of the seabed with sonar is akin to standing in Everest Base Camp directing a laser pointer at the top of the mountain and calculating the height down to the last centimetre. True accuracy is next to impossible when your vessel is pitching and heaving in the steep waves of the Southern Ocean. The only way to really map the sea floor is through the slog, the donkey work of sending out a survey ship and sounding the seafloor piece by piece.
The task is dangerous: wild, random stuff happens. A US$300,000 arm simply fell off Five Deeps’ submersible on its first dive in the Atlantic. Ahead of the same venture’s foray into the Southern Ocean, some bright spark stocked the ship’s lab with rolling chairs that careered around in the high seas like bumper cars. Heading into the depths is no Disney ride, as was illustrated this summer by the implosion of the Titan submersible.
Much of the mapping that has taken place was carried out for not entirely wholesome reasons. The British mapped Antarctic waters to facilitate whaling, while most modern surveys are undertaken by scientists or the military, the latter not renowned for embracing the principle of open-source data sharing.
What has been mapped, however, reveals a truly astonishing world of undulating valleys, active volcanoes and flat-topped seamounts. The greatest waterfall in the world isn’t Angel Falls but found on the seabed east of Greenland, where warm and cold water collide and plunge 3,500 metres over a cataract to the seabed. The fauna is implausible: huge sponges live on the seafloor for 11,000 years; the Mariana snailfish, the world’s deepest-dwelling fish, resides at 8,000 metres; the Great Barrier Reef hosts a coral stack taller than the Empire State Building. First-hand accounts of seabed dives poetically describe ‘plankton raving past the viewport looking like stars moving at warp speed’.
Trethewey is a nuanced writer who writes fine-art-level sketches of the dramas and encounters as they unfold. She also has the strong journalist’s knack of cajoling her cast of characters to talk about the magical world they’re trying to chart, so this is a book not just about mapping the seafloor, but also the everyday lives of those who seek it out – the nuts and bolts of how mapping is made to happen.
Although some of those featured have egos so big they would get wedged in the Mariana Trench, I found myself cutting these sometimes flawed, irrational human beings some slack. Given the chance, would you seriously take a submersible into and beyond the ‘crush zone’ to the Hadal Zone, where, as Trethewey balefully puts it, ‘the seafloor goes to die… sucked down into the Earth’s molten core and recycled’?
The future of humanity may depend on not only protecting what’s down there – in order to maintain the rhythms of global ecosystems, of vast food chains – but simultaneously, on exploiting it judiciously, sustainably. Mineral companies are licking their lips at the potential riches but may, we learn, be in for something of a shock; it’s difficult to make the economics add up.
So much remains unexplored, unknown. The seafloor is reckoned to be the resting place for three million shipwrecks; evidence of pre-contact tribes sits on the now-submerged continental shelf. Trethewey explores, but doesn’t overegg, the psychological element: why humans fear the seabed but are entranced by space, how, as Nietzsche observed, ‘If thou gaze long into an abyss, the abyss will also gaze into thee.’ Mapping the seafloor, its cracks and fissures is, Trethewey argues pretty convincingly, part of the quest to understand ourselves
