[1] One document records him as a Portuguese in the service of Castile ("Spain"), having possibly been born in Lisbon or São Pedro de Solis.
However he began his naval career in Portugal as João Dias de Solis, where he became a pilot in the Portuguese India Armadas.
After leaving his home in Lisbon and the ship that he was going to sail as Pilot, in the same day of departure of the fleet (ship captained by Afonso de Albuquerque, in the 1506 armada of Tristão da Cunha, to India), accused of the death of his wife, he served as a privateer in French fleets for a short time, before serving, later, the Spanish Crown.
[6][7] Two years after appointment to this office, Díaz de Solís prepared an expedition to explore the southern part of the new American continent.
Surviving crew members reported Díaz de Solís and most of the other men had been killed, thus putting the expedition to an end.