Sebastião Rodrigues Soromenho (Sebastián Rodríguez Cermeño in Spanish; c. 1560–1602), was a Portuguese explorer, born in Sesimbra (Portugal), appointed by King Philip II of Spain (Spanish: Felipe II de España; Portuguese: Filipe I de Portugal) to sail along the shores of California, in the years 1595 and 1596, in order to map the American west coast line and define the maritime routes of the Pacific Ocean in the 16th century.
He was probably the same man as a Sebastian Rodrigues, a pilot on the Manila Galleon Santa Ana, which was captured by Thomas Cavendish in 1587 during his circumnavigation.
The Manila galleon San Agustin was sent from the Philippines to survey the coast of what became Oregon and California and then to complete the trip to Acapulco, Mexico.
He was greeted by the Native Americans in a manner similar to that offered to Francis Drake 16 years earlier, but there was an absence of the great fear and reserve exhibited on that occasion.
Several people died (accounts vary between seven and twelve) and all goods (mostly silk, wax and porcelain) were lost.