Sebastian Vizcaino was a Spanish captain and ambassador to Japan.

He travelled from Mexico to Japan in 1611 as an ambassador, and returned Japanese men who had come to Mexico earlier with the embassy of Luis Sotelo.

Sebastian Vizcaino met with Tokugawa Ieyasu and Date Masamune during his stay in Japan.

He then left the country to accomplish a mission to discover a fabled "Island of gold and silver" suppposed to be in the sea East of Japan. His ship the San Francisco was crippled in bad weather, and he was forced to rally Uraga, his original point of departure.

The following year, Sebastian Vizcaino left for Mexico on a boat the Bakufu had built for him, but he once again met with bad weather, and had to come back to Uraga.

Because of these two failures, it was decided that Date Masamune, the Daimyo of Sendai would build a stronger ship. This ship became the San Juan Bautista, a 500-ton galleon-type warship, which was used on the same occasion to dispatch a Japanese embassy to Mexico and then Europe, led by Hasekura Rokuemon. It is said Sebastian Vizcaino contributed his knowledge of ship technology and navigation skills to the building of the ship and the success of its mission.

Sebastian Vizcaino wrote a report tittled "Account of the search for the gold and silver islands", in which he related his adventures in Japan.

Vizcaino did not discover San Diego Bay, he named it. The first European discoverer was Juan Rodriguez Cabrillo in 1542, sailing for Spain and sometimes thought to have been a Portugese but now more accepted as having been born in Spain.