What were the primary three reasons for the Spanish to be exploring North America?

The primary three reasons for the Spaniards to be exploring North America (and, by default, Central and South America) stem from imperial ambitions. Spain, like Portugal and other European countries (especially England, France, and the Netherlands), was a seafaring nation. At the time, Spain had begun to set its sights outside of its borders in order to expand trade and gain territory ahead of its chief rivals, namely, the Portuguese. Imperial ambition was the first primary reason. In this spirit, Christopher Columbus sought a western passage to India, so he set sail across the Atlantic—only to find the Americas. Alongside ambition, wealth from land, gold, or silver was on his and other explorers' minds. Gaining wealth was the second primary reason. As Spain made inroads in the "New World," laborers, basically slaves, were needed to build, mine, and cultivate on the scale that Spain (and other countries) envisioned. One way to bring the native population under submission to the explorers and, later, to the colonists, was by converting them to the faith of the colonists: Catholicism. Conversion would lead to obedience; obedience would facilitate labor. So, the third primary reason was spreading the Catholic faith by converting the natives. Officially, this sounded good and reasonable; unofficially, it was an excuse to manipulate the native population to do the bidding of the colonizing power.