Pytheas of Massalia (modern-day Marseille) was an ancient Greek geographer, astronomer and navigator who, around 325 BC, undertook one of the most audacious voyages of antiquity. Sailing past the Pillars of Hercules and northward through waters no Mediterranean Greek was known to have charted, he reached the British Isles, circumnavigated Britain, and pressed on toward a northern land he called Thule — possibly Iceland, Norway, or the Faroes.

His lost work On the Ocean (Περὶ τοῦ Ὠκεανοῦ) recorded the first known scientific observations of the polar regions: the midnight sun, the frozen sea, and — crucially — the link between the Moon and the tides. He measured the latitude of Massalia with a gnomon to remarkable accuracy.

Pytheas pushed past the edge of the known world to measure what others would not. The Pytheas engine carries his name because risk, like the ocean, is best understood by charting its extremes.