The unique volcanic island of Madeira is located about 950 kilometres from the Portuguese coast in the middle of the Atlantic Ocean and is most famous perhaps for the most fascinating and long-lasting fortified wines in the world. The island first gained importance with the emerging shipping traffic to South Africa and India; the wines were needed for the long voyages. The port city of Funchal thus became a sought after port of call for sailing ships. As a result, almost every suitable spot on Madeira was planted with vines to supply the ships. However, as it became clear that the wine would survive the sea voyage if it had a higher alcohol content, alcohol was added to it, in other words, fortified. At the same time, the wine proved to have a better taste when it passed the equator on the ships, as opposed to ageing on the island. This Vinho de Roda was in such demand that, after the enormous damage caused by the phylloxera disaster had been recovered, Madeira's producers devised a system for carrying out this type of ageing on land as well. The result is the "Estufa", a system in which the fortified wine is heated, caramelising the sugar in the wine. Today there are still the classic estufas in warm warehouses, while others heat the wine in tanks with a warming system. Sercial, Verfelho, Bual and Malmsey are the white wine varieties permitted for the production of Madeira, with the first variety representing the driest Madeiras and ascending to Malmsey that produces the sweetest. Mass-produced wines account for 40 percent of production. The really good Madeiras, however, matured over many years, develop their special charms only after decades and are then among the most precious rarities in the world.