Most historical accounts indicate that Colombo changed his name to Colón when he moved to Spain and became a citizen. The reasons remain unclear, although he most likely did it to make himself sound more Spanish, just as many European immigrants to the early United States anglicized their last names or changed them entirely. 

Cristóbal Colón de Carvajal y Gorosábel, 18th Duke of Veragua, 17th Duke of la Vega, 19th Marquess of Aguilafuente, 16th Marquess of Jamaica, 20th Admiral of the Ocean Sea, GE, OIC (born October 4, 1949) is a Spanish nobleman, businessman and formerly an officer, helicopter pilot, and commander of a naval vessel in the Spanish Navy. He is a direct descendant of Christopher Columbus by way of Christopher's son, Diego.