Westward and Eastward Exploration Met

Soon after Magellan's expedition the Portuguese rushed to seize the surviving Spaniards and build a fort in Ternate. In 1525, Charles I of Spain sent another expedition sailing westwards led by García Jofre de Loaísa to colonize the Maluku Islands, claiming that they were in his zone of the Treaty of Tordesillas. The fleet of seven ships and 450 men included the most notable Spanish navigators: Juan Sebastián Elcano and Loaísa, who lost their lives there, and the young Andrés de Urdaneta. Near the Strait of Magellan one of the ships was pushed south by a storm, reaching 56 ° S, where they thought seeing "earth's end": so the Cape Horn was crossed the first time. The expedition reached the islands with great difficulty, docking at Tidore. The conflict with the Portuguese already established in nearby Ternate was inevitable, starting nearly a decade of skirmishes.

As there was not a set eastern Tordesillas limit, both kingdoms organized meetings to resolve the issue. From 1524 to 1529 Portuguese and Spanish experts met at Badajoz-Elvas trying to find the exact location of the antimeridian of Tordesillas, which would divide the world into two equal hemispheres. Each crown appointed three astronomers and cartographers, three pilots and three mathematicians. Lopo Homem, Portuguese cartographer and cosmographer was in the board, along with cartographer Diogo Ribeiro on the Spanish delegation. The board met several times, without reaching an agreement: the knowledge at that time was insufficient for an accurate calculation of longitude, and each group gave the islands to its sovereign. The issue was settled only in 1529, after a long negotiation, with the signing of Treaty of Zaragoza, that attributed the Maluku Islands to Portugal and the Philippines to Spain.

Between 1525 and 1528 Portugal had sent several expeditions around the Maluku Islands. Gomes de Sequeira and Diogo da Rocha were sent north by the governor of Ternate Jorge de Meneses, being the first Europeans to reach the Caroline Islands, which they named "Islands de Sequeira". In 1526, Jorge de Meneses docked on Waigeo island, Papua New Guinea. Based on these explorations stands the theory of Portuguese discovery of Australia, one among several competing theories about the early discovery of Australia, supported by Australian historian Kenneth McIntyre, stating it was discovered by Cristóvão de Mendonça and Gomes de Sequeira.

In 1527 Hernán Cortés fitted out a fleet of three ships to find new land in the "South Sea" (Pacific Ocean) and asked his cousin Alvaro de Saavedra to take charge. On October 31 of 1527 Saavedra sailed from New Spain, crossing the Pacific and touring the north of New Guinea then named Isla de Oro. In October 1528 one of the vessels reached Maluku Islands. In his attempt to return to New Spain he was diverted by the northeast trade winds, which threw him back so he tried sailing back down, to the south. He returned to New Guinea and turned to the northeast, where he sighted groups of the Marshall Islands and the Admiralty Islands and again was surprised by the winds, which brought him a third time to the Moluccas. The westbound return route was harder to find, but was eventually discovered by Andrés de Urdaneta in 1565.