This story of the 1970 expedition of Hudson is really a memoir of a young man for whom the voyage was a primer on the oceans, their science, and the real world of people outside the sheltered life of a Cambridge schoolboy. The tale is told from the standpoint of a ‘young recruit’ to the marine sciences. In 1969, Peter Wadhams was finishing his degree in physics at Cambridge and was looking for a career. Instead he stumbled into an adventure of a lifetime. It happened that he attended a lecture by geophysicist Edward Bullard on seafloor spreading, and asked him for a job. Bullard declined but recommended Wadhams contact a Canadian, Bosco Loncarevic, who worked at the Bedford Institute of Oceanography, in Nova Scotia. The end result was that Loncarevic asked the young Wadhams to take part in the Hudson-70 expedition. It seemed that no one wanted to stay aboard for the entire trip, around both of the American continents, and Loncarevic needed a junior person aboard to keep records and make sure there was some continuity in measurements. Should he accept the post, Wadhams would be forced to endure the voyage the whole route, as it travelled the oceans and visited Rio de Janeiro, Buenos Aires, Antarctica, Tahiti, and other locales that others might spend their whole lives only dreaming about. The result was not only a scientifically interesting voyage, but also it was the start of a strong scientific career for Wadhams, and an eye-opening personal journey.

Those interested in the history of oceanography should approach this account with caution. It is organised logically, following the route of the ship itself, and its chapter titles helpfully call to mind the location in question. But this is where the logical coherence ends. Although Wadhams is full of humour, and his tale is often colourful, there is not much binding the narrative together. The title, The great ocean of truth, has little bearing on the expedition itself, but is a reference to a quote from Isaac Newton, who had written that ‘the great ocean of truth lay all undiscovered before me.’ Wadhams does not dwell on particular scientific questions, or on any particular issues at all. Most of the book is a highly detailed account of the comings and goings of young Wadhams, with fleeting reference to the scientific work being done by others on board. Although readers will learn a little about echo sounders and the importance of the Antarctic Convergence, they will have to find these nuggets hidden in passages that describe anything and everything, whether it is going to a bank to exchange money or visiting a house of ill repute with the lads. It is obvious that Wadhams either has a memory like a steel trap, or he kept an extraordinarily detailed diary. Despite the benefit of some critical distance, his descriptions of the people he met are very much from the perspective of an impressionable young man.

Perhaps understandably, the early chapters tend to be heavy on descriptions of tourist attractions and local people, particularly in the quest for female companionship, as the expedition traveled in South America and stopped in Brazil, Argentina, Chile, and Peru. But also we have Wadhams providing fascinating descriptions of the Chilean fjords, and the strange oceanographic phenomena that accompany them. To one who knows nothing of fjords (including this reviewer), it is useful to encounter the weird sloshing of water through the eyes of young Wadhams, and to experience their puzzling dynamics vicariously. It is equally helpful to have them explained by the mature Wadhams.

Since the great expanse between Peru and Vancouver was interrupted only by a brief interlude in Tahiti, Wadhams devotes more attention here to the scientific work. At first they headed southwest to reach once again the cold and turbulent Antarctic. The crew hauled out the magnetometer, gravimeters, and expendable bathythermographs, and put the echo sounder into full use again. The gravimeters would help scientists, led by William von Arx, to discern a somewhat clearer picture of the shape of the earth itself in the Pacific. Of all the scientists who worked on Hudson, Wadhams writes, Von Arx ‘alone possessed all the characteristics of nobility,’ and appreciated to his shipmates as one who had an extraordinary breadth of knowledge in science and culture (page 241). His work was in part designed to help calibrate a new mode of earth observation: satellite oceanography. This was in the era when dreams of a devoted oceanographic satellite overstepped the reality. Seasat, which was to draw from Hudson's work, was delayed until 1978, and even then it failed a few months after launch. The Hudson's gravimetric work would not really become crucial for satellite oceanography until the 1990s. But the Hudson made other notable measurements with the echo sounder: in an area previously thought to be fairly uniform, it measured a mountain (Hudson Peak) and a trough (Hudson Deep).

In a chapter called ‘A geophysical interlude,’ Wadhams provides more of a taste of the scientific import of the voyage. By 1970 the theory of plate tectonics, having passed from its previous incarnations of continental drift and seafloor spreading, had only recently been proposed in a comprehensive way, as a system of crustal blocks interacting on the surface of a sphere. Three of these blocks, or plates, joined together off the west coast of Canada (Juan de Fuca, American, and Pacific plates), making it a particularly interesting site for taking measurement of gravity, magnetism, seismic refraction and reflection, and heat flow. The seismic work helped to determine how the crust moved in relation to the mantle below. The heat flow measurements were abnormally high, and several years later scientists determined that the Hudson must have been moving over some active hydrothermal vents.

The voyage turned out wonderfully for Wadhams. Aside from tasting life at sea, he got to know von Arx a little, and learned to appreciate wide-ranging ideas, rather than what Wadhams considers the narrow specialisations of today's oceanographers. Wadhams sees the Hudson-70 expedition as the last of the great oceanographic voyages, part of a dead tradition that began with the Challenger in 1872. That may be, though Wadhams was probably one of a select view who saw it that way, since he was there for the duration. Scientists were able to fly in and climb aboard for discrete legs of the voyage.

As a memoir, The great ocean of truth is a fun jaunt through the past, and it helps to put human faces on the story of a scientific cruise. As history, its contextualisation is understandably anecdotal. Some may find it jarring to read Wadhams conflating Alfred Wegener's 1910s theory of continental drift with the 1960s ideas of seafloor spreading, which have very different conceptual bases. As a record of the voyage itself, it succeeds admirably in taking in some of the science, and some snapshots of the western hemisphere's ports-of-call, seen from the perspective of a ship full of men doing science and having the time of their lives.