Young combines arrays of charts, color photos and diagrams with descriptive captions, general comments, notes on technical gear and short interviews to explore the many ways all who travel on or in the ocean keep track of their courses and locations. Referring occasionally to five particular examples—a hatchling loggerhead turtle, a huge container ship, a sailboat, a shark and a nuclear sub, all in the Atlantic—she covers not only navigational methods, from echolocation to GPS systems, but a host of related topics as well, from currents and storms to deep-ocean dwellers, whale tracking, map-reading skills and the history of submarines. Though backgrounds on some pages make the text hard to read, young fans of all things nautical will happily immerse themselves in this seagoing omnium gatherum. (index, multimedia resource lists) (Nonfiction. 9-11)