The Sea Inside

hundred and seventy million cubic miles of water, and covers sixty-three million square miles, a third of the planet’s surface. It descends to the greatest depths, the Mariana Trench, nearly seven miles down, a place visited only twice by human beings, a lightless sea bed less mapped than the moon. This ocean also holds the oldest water: such are its slow-moving undercurrents that the oxygen in its middle layer has been there since that water was last in contact with the air at the surface up to a thousand years ago. It is as much an archive of the ancient atmosphere as the air bubbles trapped in ice cores taken from the Antarctic. Given these superlatives and immensities, it is not hard to believe that of the million species in the sea, three-quarters are yet to be described, and one third remain unknown to science. Even its sepulchral abysses support life forms alien to our imaginations: colourless creatures, living far from the sun and the photic layer, feeding off another energy entirely from volcanic vents. Life itself may have begun in such places.
    Yet the Pacific is by no means a landless, uninhabited expanse. It is studded with twenty-five thousand islands, large and small, each with its own stories, of people, and animals. Their narratives crisscross the ocean in an embroidered web, drawn together in invisible lines of connection from shore to island to sea, transversed in ancient feats of navigation and migration that put our modern, computer-assisted efforts to shame. Here the remotest journeys ended; and here many began, too.

    Out of the silence and darkness of the night, I’m plunged into a hubbub of people and cars and cargo, all jostling to join the ferry that rises from the quayside. An hour later, and the ship is pushing out from harbour. The sun seeps back into the sky, and the ocean opens up to meet us. I settle on the top deck to drink tea, lazily raising my binoculars – only to see a huge grey shape in the mid-distance. It takes me a moment to realise that it is a whale.
    A voice crackles over the Tannoy to alert the passengers to the sight. They lurch over the rail for a better look. The sperm whale’s blow fizzes in the air. It raises its head, shiny with seawater, but it doesn’t really look like a whale. The passengers soon lose interest, and drift back to their breakfasts.
    I watch as the whale slips into the distance and, with a final flourish of its flukes, dives. Such a sight is rare in these waters nowadays. Yet a century ago, ships plying this route were often accompanied by another cetacean – one which acquired a near-mythical status.
    From 1888 to 1912, a Risso’s dolphin appeared regularly in the Cook Strait, the turbulent channel that separates New Zealand’s two islands. Nicknamed Pelorus Jack after Pelorus Sound, it was seen by thousands of passengers, including Rudyard Kipling and Mark Twain. Some claimed it as a kind of guardian angel, guiding ships across the dangerous waters, but it is more likely that the animal was surfing the compression wave created by the vessels’ bows, as many dolphins do. A third theory suggested a more emotional connection: that it had lost its mother and was seeking a surrogate – an idea encouraged by accounts of unweaned cetaceans attempting to suckle at the sides of the same whaleships that had made them orphans.
    Other remarkable abilities were claimed for Jack. That he could choose between two ships as to which would make a better scratching-post to rid his body of parasites, and that he preferred to follow steamers because of the sound they made. He even attracted the attention of London’s Linnean Society, whose president, Sidney Harmer, the director of the Natural History Museum, noted: ‘In the light of this story, we may have to review our incredulity in regard to the classical narratives of the friendliness of dolphins towards mankind.’ But Pelorus Jack would be both endangered by and rewarded for his dalliance with humans. After a drunken passenger on the ferry SS
Penguin
took a pot shot at it in 1904, the dolphin became the first marine mammal to become protected by law: a hundred-pound fine awaited anyone who interfered with it. It was reported that Jack declined to escort
Penguin
thereafter; five years later the ship was wrecked off the South Island, with the loss of more than seventy lives.
    For the native people of New Zealand, Pelorus Jack evoked an older myth, one which reflected their ancient relationship with