You’ve authored ‘Tracks on the Ocean: A History of Trailblazing, Maps and Maritime Travel’ — how were markings visualised on ‘boundless seas’?■ The idea of leaving tracks on the world as we move is not an intuitive one. We do so on land if we’re on a surface where our footprints remain but on water, it’s a strange idea. This began entering usage to understand navigation on water surfaces which are simply huge. The growth of oceanic navigation was important in the development of the idea of ‘tracks’. Obviously, it’s a fiction as you’re still not leaving a line on the sea but it became a tool to understand where you’re going, where you’ve been — and what you claim to have seen and occupied. A ‘track’ could turn the sea into territory.
What were some turning points in sea-mapping?
■ A crucial moment came in the early 16th century. A Spanish expedition, led by a Portuguese navigator, Ferdinand Magellan, went out in 1519.