What was the main goal for Portuguese voyages?

According to the BBC, early Portuguese explorers were mainly concerned with finding a maritime course around Africa to India and the East. Previously, the country had dealt along the overland route through Europe and the Middle East, but the Ottoman invasion of Turkey in the mid-15th century cut off this profitable trade route. The first European explorer to round the Cape of Good Hope at the southern tip of Africa was Bartolomeu Dias. He made it around the southern tip of the continent, but declining supplies and dissatisfaction among the crew threatened the expedition. Nearly a decade later, Dias advised Vasco da Gama, another Portuguese explorer trying the same act. This second expedition eventually reached India in 1498, establishing the maritime trade course and giving Portugal an advantage in the spice trade. Eventually, the experiences of these two explorers inspired another sailor, Christopher Columbus, to seek royal patronage for an expedition of his own to find a new route to the East.