Volume 1, The Explorers, presents more than 950 biographical entries that begin with birth and death dates, nationality, occupations, and areas of the world explored, followed by an account of the subject's exploration activities. Among the explorers who are covered are the well known, such as Neil Armstrong, Ferdinand Magellan, and Ernest Shackleton, but also the less familiar, such as Ahmad Ibn Fadlan (fl. 920s), whose record of his diplomatic mission from Baghdad to Russia and eastern Europe is the earliest account of that region in pre-Christian times, and Koncordie Dietrich (1821-91), a German naturalist whose travels through the Australian outback resulted in the largest collection of flora and fauna assembled by a woman. Entries range from two or three paragraphs to four pages in length and are accompanied by 144 illustrations and photographs. Appendixes list explorers by occupation, by region of activity, by nationality or sponsoring country, and in chronological order by birth date. Volume 2, Places, Technologies, and Cultural Trends, has more than 260 A-Z entries on such topics as Aerial photography, Circumnavigation of the world, Drift ice, Fur trade, Native peoples and exploration, Orinoco River, Virginia Company, and Women explorers. Entries range in length from 2 paragraphs to more than 10 pages and are accompanied by 67 photographs and illustrations and 62 maps. An appendix contains maps by region; by ancient routes in the Mediterranean, Europe, and Asia; by new water routes; and by the interior in Asia, the Americas, the Pacific Ocean and Australia, Africa, the Arctic, and the Antarctic. The volume concludes with a very thorough chronology of exploration, a further reading list for the set, a list of volume 2 entries by subject, and a 35-page cumulative index for both volumes. In both volumes, capital letters are used in the text to designate terms that are also entry headings.