Explores methods and devices scientists use to explore the ocean, walking readers through the history, current developments, and potential for future discoveries, as well as the challenges scientists currently face. Includes infographics, discussion questions, and two "Scientist Bio" features highlighting people who've done important work studying the deep sea.

A hidden world -- Mysteries beneath the sea -- Diving deeper -- Underwater observation -- Robot scouts -- Scientist bio Amanda Demopoulos -- Ocean secrets -- Scientist bio Lihini Aluwihare -- A blue future -- Focus on exploring ocean depths -- Glossary.