In his Otago surveys, Kettle made the first extensive use in New Zealand of trigonometrical methods and his urban and rural surveys have been described as 'painstaking'. He travelled extensively over the rugged Otago Block, whose daunting contours scarcely warrant a mention in his correspondence. He climbed Mount Maungatua on the Taieri Plain in 1847 and from there saw the interior of Central Otago. He identified the land as suited for pastoralism and correctly saw that as the colony's future economic mainstay. By March 1848, when the first immigrant ships arrived, the surveys' outlines were virtually complete.