Launching 50 tonnes of blubber, flesh and bone into the air, the leviathan leaves its domain, its 15ft flippers like gnarled wings, the tips of its tail, three times as wide as a man is long, barely in contact with the water.

No one really knows why whales leap. Almost every species does it — from the smallest dolphin to the greatest blue whale — in their own style: backward breaches, bellyflops, half-hearted lunges or full-blown somersaults. It may be that the animals are trying to dislodge parasites; the force is enough for breaching whales to slough off skin, convenient samples to be gathered for genetic tests. There is no knowing when they will breach, although they may do so repeatedly, often when the wind picks up, as if, like some Cetacean Mary Poppins, a change in the weather summons their magical appearance.

It seems likely that their aerobatics are an energetic means of communication — advertisements of physical power and presence, telling other whales, “Here I am,” and “Aren’t I splendid?” But when you see a whale leap out of the water like a giant penguin, your first thought is that it looks fun. That calves and young whales are more prone to breach reinforces this idea. The whales may be merely playing. Or perhaps they pity us for our enslavement to gravity, allowing us a glimpse of their true nature by rising out of the ocean to reveal their majesty.

Seeing whales in the wild seemed to turn me back into a boy. I remembered what it was that fascinated me about these outlandish animals: their sheer variety, their wildly differing shapes and sizes; a satisfying set to be collected like bubblegum cards, a catalogue of complexity and colour: from the tiny harbour porpoise to the great rorquals — from the Scandinavian for reed or furrowed whale, a reference to their ridged bellies — and the mysterious sperm whale, a tiny model of which I found in my sister’s toy box, still perched on its plastic wave.

Lowering its broad, flattened snout, the whale dips below the keel in one imperceptible motion, as if powered by an invisible, silent motor. The finback completes its manoeuvre, emerging on the larboard side of the boat to breathe; unlike humans, whales must make a conscious decision to respire, otherwise their dives would be impossible. With a plosive whoosh as it fills its lungs, the finback shoots out a mixture of air and salt water and a little whale phlegm, its shiny blowholes closing in an airlock as it prepares to dive. The spume hits my face like a fishy atomiser. I have been breathed upon, and it feels like a baptism.

It is difficult not to address whales in romantic terms. I have seen grown men cry when they see their first whale. Nothing else represents life on such a scale. Seeing a whale is not like seeing a sparrow in a city tree, or a cat crossing the street. It is not even like seeing a giraffe, dawdling on the African veld. Whales exist beyond the normal. They are not so much animal as geographical; if they did not move, it would be difficult to believe they were alive at all.

Here was an animal close to me as a living creature — one that shared my heart and lungs, my mammalian qualities — but which at the same time was possessed of a supernatural physicality. Whales are visible markers of the ocean life we cannot see; without them, the sea might as well be empty for all we know. Yet they are entirely mutable, dreamlike because they exist in another world, because they look like we feel as we float in our dreams. They are Linnæan-classified aliens following invisible magnetic fields, seeing through sound and hearing through their bodies, moving through a world we know nothing about. They are animals before the Fall, innocent of sin.

But they also have bad breath, and shit reddish water. They eat day and night without discretion. They are super-sized animals, “charismatic megafauna” in the zoologists’ dismissive phrase. They cannot, like the old joke, be weighed at a whale weigh-station, although they once were placed on scales in pieces, like legs of lamb. Out of their element they collapse under their own weight, lacking limbs to support themselves, pathetically incapable of self-preservation despite, or because of, their great size. For all their physical reality, they cannot be encompassed, or even easily described. We may stand around in awe and pick apart their carcases, but in the end all we are left with to show for our curiosity are bones that give little clue to the true shape of their living owners.

Whales existed before man, but they have been known to us only for two or three generations: until the invention of underwater photography, we hardly knew what they looked like. It was only after we had seen the Earth from orbiting spaceships that the first free-swimming whale was photographed underwater. The first underwater film of sperm whales, off the coast of Sri Lanka, was not taken until 1984. We knew what the world looked like before we knew what the whale looked like. Even now there are beaked whales, or ziphiids, known only from bones washed up on remote beaches — esoteric, deep-sea animals with strange markings that biologists have never seen alive or dead, so little studied that their status is “data deficient”. We would do well to remember that the world harbours animals bigger than ourselves, which we have yet to see; that not everything is catalogued and claimed and digitalised. That in the oceans great whales swim unnamed by man.

© Philip Hoare 2008 This is an edited extract from Leviathan or, The Whale, published by Fourth Estate at £8.99. To order it for £8.54 inc p&p call 0845 2712134 or visit timesonline.co.uk/booksfirst

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