In 1792, after exploratory voyages by Spaniards Manuel Quimper (1790) and Francisco de Eliza (1791), the extent of Juan de Fuca Strait remained a mystery. Some still believed the strait held the entry to the fabled Northwest Passage. Moreover, pressures caused by the Nootka Sound Controversy suggested the strait as a possible boundary between Spanish and British territories. Alejandro Malaspina, who had completed his own voyage to the Northwest Coast in 1791 (see Malaspina Expedition), recommended Dionisio Alcalá-Galiano and Cayetano Valdés to command the small schooners Sutil and Mexicana. They were to survey the strait and the coast south to San Francisco. In early June 1792 they visited the Spanish post of Nunez Gaona [Neah Bay, Wash] and, guided by Indian chief Tetacu, they crossed to Vancouver Island. After charting many of the Gulf Islands, on June 22 the Spaniards sighted George Vancouver's Discovery and Chatham near present-day Vancouver. Each side was mortified to discover its major competitor, but relations were amicable. The 2 groups shared provisions and information before continuing separately to circumnavigate Vancouver Island. The 4-month Spanish expedition produced a wealth of geographical and ethnological information but no evidence of usable resources. The voyage became better known than other Spanish expeditions since the government permitted publication of the journal recording the voyages in 1802.

See also Spanish Exploration.