Diego Ramírez de Arellano Chamás

Diego Ramírez de Arellano
Diego Ramírez de Arellano (center) from an 18th-century ceramic altarpiece commemorating the sons of Xàtiva
Born	c. 1580 Xàtiva, Valencia, Spain
Died	27 May 1624 Seville, Spain
Nationality	Spanish
Occupation	Navigator
Known for	Discovery of the Diego Ramírez Islands

Diego Ramírez de Arellano (c. 1580 – 27 May 1624) was a Spanish sailor and cosmographer. He achieved fame for piloting the Garcia de Nodal expedition to the region of the Strait of Magellan. The expedition discovered the Diego Ramírez Islands, the most southerly point visited by Europeans until the discovery of the South Sandwich Islands by Captain James Cook in 1775.

The Strait of Magellan was discovered by the Spanish in 1520, providing a sea route between the Atlantic and the Pacific that ran between South America and the archipelago of Tierra del Fuego. The strait averages just over 4 miles (6.4 km) wide, and is much narrower in places, forming a "V" shape pointing south. There are westerly or southwesterly winds most of the year, often stormy. The tidal currents are strong and unpredictable. The strait is a difficult and dangerous passage for a sailing vessel. Early in the seventeenth century it became known that the Dutch navigators Jacob Le Maire and Willem Schouten had found a new and safer route farther south. Philip III of Spain arranged for an expedition of two ships to verify the discovery, which left Lisbon in September 1618.

Diego Ramírez de Arellano was born in Xàtiva in Valencia around 1580. He was appointed the main pilot in the 1618 expedition led by the brothers Bartolomé and Gonzalo García del Nodal to explore the region of the Straits of Magellan. The expedition consisted of two caravels. Ramírez was charged with astronomical observations and with preparing charts with the help of Juan Manso and seven other pilots, four in each caravel. They had modern astrolabes that could measure angles of five minutes of arc, giving much more accuracy than older instruments.