Salvador Fidalgo joined the Real Colegio de Guardiamarinas in Cádiz in the year 1770. He graduated five years later as a midshipman. He was chosen as a member of the cartography team of Vicente Tofiño, author of the first atlas of the ports of Spain which probably gave him the necessary expertise for the work he would do in Nueva España.

In 1778, he was promoted to ship lieutenant, and he was sent to the naval station of San Blas, in the Mexican Pacific coast. Afterwards, he would never return to his homeland. He was destined to travel, explore, found, and give Spanish names to places further to the north than any of his countrymen had ever gone.