Final answer:
Portugal was the country, besides Spain, also interested in finding a sea route during the European Age of Discovery. Portugal played a significant role in Atlantic exploration and established trading ports in various strategic locations, rivaling Spain's efforts.
Step-by-step explanation:
Alonzo Alvarez de Pineda, like many explorers of his time, was part of the European Age of Discovery, where various countries were interested in finding sea routes for trade, exploration, and establishing colonies. The country besides Alonzo Alvarez de Pineda that was interested in finding a sea route was Portugal. This nation, under the sponsorships such as that of Prince Henry the Navigator, initiated the era of Atlantic exploration and was a key player in the European Age of Discovery. Using advanced navigational technologies like the compass, the astrolabe, and the caravel, Portugal established trading ports along the coast of West Africa and in India. Answering the student's question directly, the other country that was interested in finding a sea route, in addition to Spain, where Alonzo Alvarez de Pineda hailed from, would be Portugal.
On the other hand, Spain established the first colonies in the Americas, following Columbus's voyage in 1492. Portugal and Spain's competition was eventually resolved with the Treaty of Tordesillas and the Treaty of Zaragosa, which divided the earth into two zones of influence. This set the stage for other European countries like England and France, which emerged as sovereign nation-states with strong monarchies, to later engage in overseas expansion after dealing with internal religious turmoil due to the Protestant Reformation.