During Cook’s early naval career he gained fame and skill as a surveyor in Quebec and Newfoundland. By the time he was put in charge of the expeditions to the Pacific Ocean, mapmaking was one of Cook’s special interests and responsibilities.
Due to his early training Cook was able to link nautical mapping with the increasingly sophisticated techniques being employed by land surveyors, including the establishment of a reliable baseline and the use of triangulation and trigonometric readings from a series of landmarks to establish accurate coordinates.
To create accurate maps, both latitude and longitude must be known. Navigators had been able to work out latitude accurately for centuries by measuring the angle of the sun or a star above the horizon. Longitude was more difficult to measure, as it requires precise knowledge of the time difference between points on the surface of the earth.
Cook was able to make full use of the recent advances in navigation and mapmaking to map uncharted areas of the Pacific. On his first voyage, Cook mapped the entire coastline of New Zealand as well as many smaller islands, and on the third voyage he mapped the northwest coast of North America all the way to the Bering Strait between Alaska and Russia.