Christopher Columbus was an Italian explorer who is nowadays mostly known for his "discovery" of the Americas. He claimed it was possible to reach Asia by sailing across the Atlantic Ocean and was looking for potential sponsors among the rulers of European countries. His voyage was later supported by two Spanish rulers, King Ferdinand and Queen Isabella, who had recently joined the two kingdoms of Aragon and Castile. To secure their patronage, Columbus promised them to spread Catholicism across the globe. In August of 1492, with the help of the funds from his sponsors, Columbus set sail with three different ships—Nina, Pinta, and Santa Maria—in search of a shorter route to Asia, which would help with the international spice trade.

Columbus also had other motivations for his journeys. Dreaming of glory, fame, and fortune, he was prepared to explore the far corners of the world. However, on his famous first voyage, he failed to find Asia and instead reached the shores of an archipelago which is known today as the Bahamas.

Christopher Columbus' first voyage in 1492 had several motivations. The primary reason for the voyage was to discover a shorter trade route to the Spice Islands of East Asia. Spices were a lucrative commodity in Europe. Before the days of refrigeration, food went bad quickly and spices were needed to make food more palatable for those who could afford them. For centuries, the Arabs controlled the spice trade from Asia. In the 15th Century, a race between the Portuguese and the Spanish began to find profitable sea routes to the Spice Islands. If a nation could get the upper-hand in the spice trade, then great profits and fortunes could be made. Columbus believed that by sailing West across the Atlantic he would discover a shorter route to the spices of Asia. However, he had no idea that the American continents lay in his path.

Another reason for Columbus' voyages was to spread the Catholic faith to the peoples he encountered. Queen Isabella of Spain was a staunch Catholic. In order to win her support of his voyages, Columbus promised to spread the faith to the people in the lands he came across.

The later voyages of Columbus were more about discovering more lands for the conquest of Spain than they were about spices. On his second, third, and fourth voyages Columbus explored areas of the Caribbean and South and Central American coasts in the effort to both glorify himself as a great explorer and to add more land and resources to the quickly growing Spanish Empire. The second voyage, in particular, included over one thousand Spaniards who intended to settle in these newly discovered lands.

Christopher Columbus went on his voyages for two reasons, in my opinion -- money and glory.

In the time of Columbus, the spice trade with places like India and Indonesia was extremely important and very lucrative.  Columbus believed that he could find a way to get to Indonesia by sailing west.  If he could do that, whoever sponsored him would be able to get in on the spice trade that was, at this time, mainly in the hands of the Italians (via the Middle East) and the Portuguese (by sailing around Africa).

Columbus also wanted the glory of being the first to sail that route.  He wanted to be known as a person who figured out a way to Indonesia that no one else had discovered.

All in all, then, Columbus wanted to get rich and he wanted the glory of finding a new sailing route to "the Indies."