Throughout history, people have always explored new frontiers. Adventure, fame, and scientific discovery have all driven humans to forge into the unknown. This series examines the exploration of polar regions, mountains, caves, deserts, space and under the sea. Easy-to-read, engaging text takes readers from deep beneath the oceans to outer space, examines the explorers who journeyed to these unforgiving areas, and traces the development of the technology and techniques that made these explorations possible. Well-placed sidebars, vivid photos, helpful maps, and a glossary enhance readers’ understanding of each topic. Additional features include a table of contents, a selected bibliography, source notes, and an index, plus a timeline and essential facts. Aligned to Common Core Standards and correlated to state standards. Essential Library is an imprint of ABDO Publishing Company.