As often happens in the history of exploration, the impetus comes not from government but from obsessed individuals driven by a desire for glory, both temporal and spiritual. Estensen asks, ‘What drew the sixteenth-century navigators of Spain onto the world’s largest ocean, where small, clumsy wooden vessels with relatively primitive methods of navigation faced enormous uncharted distances, unknown weather conditions, hostile natives and the hazards created by their own internecine quarrels?’

There are three expeditions described in this book, all of which set out from Peru to sail westwards to seek the south ern continent which was believed to exist, balancing the Earth’s northern land masses. The first left in November 1567, at the instigation of Pedro Sarmiento de Gamboa, who had little trouble convincing the colonial governor to send two ships ‘in search of treasure’, which he believed must be ‘at no great distance from Peru’. However, the governor gave the command of the expedition not to Sarmiento but to his own nephew Alvaro de Mendaña de Neira. They reached the Solomon Islands, and Mendaña, then in his twenties, became obsessed with the idea of returning to found a colony in the islands: ‘From this base the discovery, colonisation and Christianising of the South Land would take place.’

The second voyage was the outcome of Mendaña’s obsession, which carried him through the twenty-six years of petitioning, manoeuvring through bureaucracy, battling hostile colonial administrations and personal poverty. His marriage to Isabel Barreto, of a rich and influential colonial family, eased his financial burdens, while bringing with it a clutch of in-laws to take on the expedition.

They set out in April 1595. Navigation methods being what they were, it was never easy in this period to find the way back to previous discoveries, and they eventually found themselves not among the Solomons they knew, but on the island of Santa Cruz, four hundred kilometres west. A colony was established there, but disease, mutiny and conflict with the local inhabitants meant it was a short-lived venture. Mendaña himself died in October 1595 and the colony was abandoned soon after. When they reached Manila, with its well-established Spanish settlement, only one hundred of 378 who had set out in April had survived. One of these was the chief pilot, Pedro Fernández de Quirós, who ‘had taken in its entirety the dream of Alvaro de Mendaña de Neira’. It was now his turn to devote years of his life to the pursuit of the southern continent. Ten years of travelling and petitioning finally saw him setting out in 1605 with three vessels to explore, discover, colonise and convert millions of souls in the still mythical Terra Australis.

This time they fetched up in modern-day Vanuatu, on a land mass that Quirós called La Austrialia Del Espíritu Santo, named to honour Philip III’s connection with the Austrian royal family: no reference to the Austral or south land was intended. Nevertheless, he remained convinced he had found Terra Australis, and returned to Peru to report. Meanwhile, he had become separated from his secondary vessel, captained by Luis Váes de Torres. While Quirós head ed back east to South America, Torres headed for Manila, happening on the south coast of New Guinea and the passage through the perilous strait that now bears his name.

Estensen writes well and without pretension, but there are signs of haste in the preparation of the book. A few howlers stand out: on the first page of the acknowledgments, she refers to the expeditions at the end of the fifteenth century ‘and at the beginning of the 1660s’, which is puzzling since the expeditions she deals with took place between 1567 and 1607. Some clumsiness characteristic of a first draft remains, in phrases such as ‘roughly about 400 kilometres’ and ‘effort had to be exerted’. There is a reference map, but it could show more details. Latitudes are constantly referred to in the text, but only 10° and 21° are marked; and many of the landfalls are not included. Otherwise the editorial apparatus is good, with a glossary, bibliography and thorough index.

Estensen’s approach is sympathetic and even-handed. She explains the Spaniards’ missionary fervour: Quirós especially was motivated by compassion for the heathen to whom he could offer eternal salvation. But of course there was another side to the story, and she is careful to point out, without condemning the expeditioners, that, ‘whatever else the Spaniards might seem to be in the eyes of the islanders, they were inevitably dangerous, demanding and ultimately destructive’. Estensen notes, though, that ‘probably the greatest damage done to the islanders was not so much the killing, for they pursued their own wars, but the violent disruption of the normal pattern of their lives.’ She negotiates the competing accounts of the voyages carefully, assessing the characters of the writers and their likely motives for stretching the truth.

Terra Australis remained incognita for nearly two centuries after these voyages, but the Spanish made their own contribution to the geography of the Pacific, and Estensen’s highly readable account acquaints us with the life and times of some of the remarkable people who were driven to explore the unknown, rashly sacrificing themselves and others in pursuit of a myth.