Extreme environments, such as the polar regions, have always been real-life proving grounds for Oyster watches. The Explorer II is natural heir to the Explorer as a reliable guide, a tool and a companion for explorers, speleologists and vulcanologists. When it was launched in 1971, the Explorer II set new standards for chronometric precision, strength, autonomy and clarity. It features a distinctive 24-hour hand, an invaluable aid to distinguish daytime hours from night around the poles and beneath ground.