One of the refreshing things about Tim Severin is that one believes what he says. Which other travel writer would dare admit, for example, that in four days patrolling Pacific reefs with Filipino shark-jumpers, he failed to spot a single shark? Where rivals might be tempted to ditch the episode, Severin is matter-of-fact. ‘On the fourth day,’ he says, ‘we turned for home. The men wanted to get back to their families, and we had burned up our allowance of diesel.’

Perhaps this is because Severin is as much a sailor as a writer. His previous expeditions include a nine-month voyage from Muscat to Canton in a replica of a ninth-century Arab sailing ship, and an Atlantic crossing in a leather coracle in the wake of St Brendan, the legendary Irish monk who allegedly reached America a thousand years before Columbus. Involving years of planning, large staffs and hefty sponsorship as well as considerable physical danger (the St Brendan had no engine), these feats have deservedly won him the Royal Geographical Society’s gold medal.

Compared to these epics, Severin’s latest quest is simple. Like Melville’s novel, In Search of Moby Dick is loosely structured around a search for a white whale. To this end, Severin spends time with the last people on earth to hunt large sea animals in the same way as the nineteenth-century whalers, with hand-thrown hooks and harpoons.

That such people still exist is extraordinary in itself. The shark-jumping Filipinos of Pamilacan, a tiny chunk of coral in the Bohol Sea, patrol for whale sharks in small outrigger canoes. Having got within range, the lead jumper throws himself overboard onto the forty-foot-long animal’s back, clutching an iron hook. ’Underwater,’ Severin tells us, ‘he had two or three seconds to grapple, place the hook and drive it home. Then another five seconds to swim to the surface … before the line thundered out, and the boat was torn forward.’ Misjudgement can result in disaster: ‘If the hook was placed too far back on the body, or in the upper curve of the back, the shark was not sufficiently impeded and could swim so powerfully that the rope broke, or the thick steel curve of the hook opened out and pulled free, or the boat could be pulled under.’

Severin’s climax comes on the island of Lamalera, off the eastern end of the Indonesian archipelago. Here, hunters use engineless wooden boats sewn together with palm-fibre, and harpoon heads forged from old car-springs, to hunt sperm whales. This time, Severin is in luck, witnessing two successful hunts at close quarters. Precariously balanced on the prow of his fragile craft, the harpooner f1ings himself and his weapon upon a thirty-foot bull whale, which plunges out to sea, ‘towing like an enormous draught horse’. The crew must run out the line in such a way that it does not capsize the boat, nor amputate entangled limbs, and paddle out of range of the animal’s thrashing flukes. After an hour’s fight, the whale weakens, and is stabbed to death with knives tied to lengths of bamboo. Beached and butchered, every part of its corpse is put to use, from the tough meat, tasting of ‘very strong venison ‘, to the reeking contents of its intestines, which ‘the hill people use on their rice as a delicacy’. Later, the hunters find a sperm-whale pod, resulting in a scene straight from Moby-Dick itself. Jaws snap, the sea boil and men and paddles go f1ying, torpedoed from below by panicked cetaceans.

Like a good anthropologist, Severin tries to see thing from the hunters’ point of view. Sperm whales, he points out, number more than all the other great whale species put together, and it is industrial fishing with helicopters and explosives that threatens them, not the Lamalerans with their home-made boats and bamboo lance. Neither does he sentimentalise. In the shark-jumpers’ village on Pamilacan, he watches children patiently collect trickles of brackish water, half a cupful at a time, from dried-up wells, and the drying shark meat smells so disgusting that it makes his eyes water. Small wonder that the young men of the island increasingly look for work elsewhere.

Severin never finds his Moby Dick, but he hears plenty of stories about him. Hunters leave Moby alone, for he is king of his race, and without him the whales will disappear, never to return. And they know, like Melville, that by attempting to catch the white whale ‘you run no small risk of being eternally stove and sunk by him. Wherefore, it seems to me you had best not be too fastidious in your curiosity touching this Leviathan.’