Columbus was born in 1451 in Genoa, part of modern Italy. In one of his writings, Columbus claims to have gone to the sea at the age of 10 and later became a sailor on the Mediterranean. Shipwrecked near the Portuguese coast in 1476, he made his way to Lisbon, where his younger brother, Bartholomew, an expert chart maker, lived. In 1477 he married Philippa, daughter of Bartolomeo Muniz de Perestrello, who was, like Columbus, a sailor, and had great interest in geography. Columbus occupied himself as a draftsman, illustrating books, making terrestrial globes, drawing charts for sale, and collecting, where he could, the material for such study. Columbus's father-in-law was Portuguese governor of the island of Porto Santo, where he had founded a colony. He, therefore, was interested in western explorations, and probably from him Columbus collected some of the statements which are known to have influenced him.

Columbus was but one among many who believed one could reach land by sailing west. His uniqueness lay rather in the persistence of his dream and his determination to realize this "Enterprise of the Indies," as he called his plan. In 1485, Columbus presented his plans to John II, King of Portugal. He proposed that the king equip three sturdy ships and grant Columbus one year's time to sail out into the Atlantic, search for a western route to the Orient, and return. The king submitted Columbus's proposal to his experts, who rejected it. In 1488, Columbus appealed to the court of Portugal once again, and once again, John II invited him to an audience. That meeting also proved unsuccessful.

Columbus had sought an audience from the monarchs Ferdinand II of Aragon and Isabella I of Castile. On 1 May 1486, permission having been granted, Columbus presented his plans to Queen Isabella. After continually lobbying at the Spanish court and two years of negotiations, he finally had success in 1492. In the "Capitulations of Santa Fe", King Ferdinand and Queen Isabella promised Columbus that if he succeeded he would be given the rank of Admiral of the Ocean Sea and appointed Viceroy and Governor of all the new lands he could claim for Spain.

On the evening of 3 August 1492, Columbus departed from Palos de la Frontera with three ships: the Santa María, the Pinta ("Painted") and the Santa Clara, nicknamed the Niña ("Girl") after her owner Juan Niño of Moguer. The great era of exploration has begun.