On 10 August 1519, the expedition left Seville for Sanlucar de Barrameda, at the mouth of the Guadalquivir River, and set sail from there on 20 September. Among the company was Antonio Pigafetta, whose diary of the voyage delivers an eyewitness account of day-by-day progress.
Pigafetta describes Magellan favourably but comments that the captains of the other ships did not love him. Highborn Spanish officers probably baulked at serving under a foreign commander, and Magellan was wary about revealing his plans, because of the distance to be covered and the hazards they would face.
Even before they had crossed the Atlantic, Magellan's orders were questioned, and the course he set disputed. Their first landfall was the Canary Islands, where the ships took on provisions and supplies of pitch.
The ships navigated along the West African coast, and on 3 October sailed for Brazil. Apart from a spell of nasty weather, the Atlantic was crossed almost without serious incident.
But Magellan had word that the other captains planned to take control of the mission. He waited until Juan de Cartagena expressed mutinous ideas in the presence of witnesses, then leapt into action, relieved him of command of the San Antonio, and put him in chains.
After reaching Brazil, Magellan avoided Portuguese territory, but no one would have predicted the passage would be 1,600 kilometres farther south than the Cape of Good Hope.
On 13 December the ships reached Rio de Janeiro, where their arrival coincided with the first rain for two months, and the local inhabitants would trade enough fish for ten men for a small mirror or pair of scissors.
In January 1520 he explored the River Plate in the belief that it might be the entrance to the straits.
Having confirmed that it was a river, they sailed on. Magellan continued along the uncharted coast, and as he made his way south, the men became uneasy.