Christopher Columbus didn't know where he was going when he left, nor where he'd been when he got back.
But was Amerigo Vespucci, who died 500 years ago and after whom America was named, any better?
The Florentine mathematician born in 1454, who crossed the Atlantic a few years after Columbus and made landfall in what are now Venezuela and Brazil, has been called a liar and much else.
Yet there's little doubt he was a great navigator: a man of science reared in the intellectual hothouse of Medici Florence, honoured as "Pilot Major" by the King of Spain.
Tales of his adventures in what he dubbed the "New World" became massive best-sellers. In his youth, Vespucci was swept up in the hectic scholarly atmosphere of Florence, the rapidly evolving knowledge of geometry, maths, medicine and astronomy, and became a close friend of a cousin of Lorenzo de'Medici.
The studies were not just theoretical. Marco Polo's land route to the Far East was blocked, but all Europe knew of the fabulous riches of the Orient, and the Renaissance men of Florence and elsewhere dreamt of reaching them by sea.
The challenge of the unknown was too much to resist: in 1491, the year before Columbus made landfall, Vespucci left Florence for Seville.
Becoming a supplier to departing ships, he immersed himself in maps and charts. He left on his first voyage on May 10, 1497, as a specialist in the primitive art of navigation.
And when the voyage was as bad as it could get, "In the midst of this terrible tempest it pleased the Almighty to show us the continent, new earth and an unknown world".
These were the words that, once set in type, galvanised Europe.
For Vespucci, the coast where his expedition landed had nothing in common with the zones described by explorers of the Orient. This was far more fascinating - an unimagined world. In his description, this New World was one of extremes. On one hand, the people were in a dream-like state of bliss: with no metals except gold, no clothes, no signs of age, few diseases, no government, no religion. In a land rich in animals and plants, free of the stain of civilisation, "they live 150 years and rarely fall ill".
But turn the coin and he was in a world of devils. "They eat one another, the victor [eats] the vanquished," he wrote. The women are intensely desirable, "none among them who had a flabby breast", but they are also monsters and witches. "Being very lustful, [they] cause the private parts of their husbands to swell up to such a huge size ..."
The fantastic nature of Vespucci's descriptions throws doubt on his observations, but then doubt surrounds almost everything about his voyages. We don't know how many he undertook and it's not even universally accepted he identified South America as a new continent.
That may have been done by the man who immortalised his name, a German geographer called Martin Waldseemuller whose amateur society published a survey of world geography in 1505, including a world map with the new, southern continent labelled "America".
Vespucci's tales of sex and cannibalism in paradise had made him world-famous, and the name stuck.