Ferdinand Magellan's expedition was heavily influenced by a desire to find another route to the Spice Routes of the Orient. The New World had already been discovered by Christopher Columbus, but the actual size of the Pacific Ocean was not realised. He possibly would not have undertaken such a venture if he had realised it was so large! Anyway, I digress.
Magellan got funding from King Charles of Spain on the 22nd March 1518 and acquired five ships* for his expedition. The diary of Antonio Pigafetta a loyal crew member, is one of the main sources of information for the voyage. It tells of the Spanish captains being envious of their Portuguese commodore and several attempts at mutiny and murder of Magellan. These scurvy rogues were either executed or marooned in isolated and barren lands in 1520.
The expedition left Europe in the September of 1519. Magellan chose to not tell the crewmen the real purpose of the voyage at first, fearing they would abandon ship and mutiny due to the exploratory nature of their expedition. By December 6 Brazil was sighted, but Magellan chose to sail on to a port (now Rio de Janeiro) further down the coast to take on supplies and water in order to avoid Portuguese settlers of Northern Brazil who may have raised unpleasant questions due to him sailing with the Spanish! They then continued south down the South American seaboard into the Southern Ocean, but weather conditions became so cold and stormy they decided to winter in Patagonia. They settled at San Julian in March 1520.
Magellan sent one of his ships on a reconnaissance voyage down the coast, but it was wrecked due to rough seas in May. The remaining ships continued and in October, during a wild storm, two ships were nearly lost as they were driven towards the land by strong tides and currents. Luckily there was a break in the coastline that they managed to steer to, and the Strait of Magellan was found. The strait is made up of hundreds of islands, closely packed together, and is subject to uncertain winds named williwaws that can blow from any direction and scupper ships on lea shores if the steersman is not paying attention. It was so hard that one of the ships abandoned the fleet and sailed back to Spain taking with it many of the expedition's provisions. This was to prove disastrous once the remaining ships reached the Pacific Ocean.
After traversing the strait, a voyage of some 38 days, and scavenging for food and game from the surrounding lands, the three remaining ships reached the Pacific Ocean. In November, the ocean was relatively calm and placid which inspired Magellan to name it 'Pacific'. Unfortunately Magellan suspected that they were much closer to the Spice Islands than they actually were and set off on a journey that would take nearly four months, without adequate supplies.
Conditions soon deteriorated on board the remaining ships. There was very little food, the men resorting to living on leather, rats and putrid biscuits. The freshwater soon turned bad and scurvy took hold due to the lack of Vitamin C. In January they restocked their supplies at an unknown Pacific island, but did not take on any fresh fruit or vegetables so were continually beset by scurvy. After making landfall at Guam in March 1521, they finally arrived in the Philippines on the 28th of that month.
From here the tale of Magellan ends as he got involved in island politics and was killed in battle on April 27th, 1521. His remaining crewmen continued on in just two ships, their numbers being so depleted. By November 1521 they had reached the Spice Islands, loaded up with spice and continued on to Spain with their valuable cargo. In order to be sure of actually getting back to Spain with news of the voyage it was agreed that one ship should sail East, back across the Pacific, and the other West around the Cape of Good Hope. The Pacific bound ship was seized by the Portuguese, most of her crew being killed, but the other finally arrived back in Spain on the 6th September 1522, having dodged enemy ships in the Indian Ocean.
Magellan's Route was not really used until the late 16th Century, but is the only real alternative to the perilous seas of Cape Horn**. A great account of a voyage through the straits can be read in Joshua Slocum's book 'Sailing Alone Around the World'.
* These were the Trinidad, the Victoria, the Santiago, the San Antonio and the Concepcion.
**Unless you want to go by the far more Northerly route of the Panama Canal!