Any novel by Andrew McGahan is likely to be a surprise, if you know his previous work, but if you were to approach this book knowing nothing about the author, there would be little about it to disturb your expectations. The cover, with its heraldic design against a marine backdrop, immediately signals its genre, and the maps on the endpapers, showing McGahan’s imagined geography of a place called New Island, confirm that this is an old-fashioned boys’ adventure novel of the heroic seafaring type. A preamble, titled ‘Fair Warning’, neatly excuses McGahan from any pretensions to oceanographic accuracy: ‘The Great Ocean rose and fell with different waves then, and different creatures moved in its depths … The ocean Dow sailed should not be confused with the lesser seas of today.’