Before the development of petroleum, the island was largely devoted to pearl fisheries and, as late as the 19th century, was considered to be the finest in the world. In 1903, German explorer, Hermann Burchardt, visited Bahrain and took many photographs of historical sites, including the old ''Qaṣr es-Sheikh'', photos now stored at the Ethnological Museum of Berlin. Prior to the First World War, there were about 400 vessels hunting pearls and an annual export of more than £30,000.