Read this: The first European to visit the region was Portuguese-born explorer Juan Rodríguez Cabrillo sailing under the flag of Castile. Sailing his flagship San Salvador from Navidad, New Spain, Cabrillo claimed the bay for the Spanish Empire in 1542, and named the site 'San Miguel'. In November 1602, Sebastián Vizcaíno was sent to map the California coast. Arriving on his flagship San Diego, Vizcaíno surveyed the harbor and what are now Mission Bay and Point Loma and named the area for the Catholic Saint Didacus, a Spaniard more commonly known as San Diego de Alcalá. On November 12, 1602, the first Christian religious service of record in Alta California was conducted by Friar Antonio de la Ascensión, a member of Vizcaíno's expedition, to celebrate the feast day of San Diego.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): Who wasn't the harbor named for?
unanswerable