As a child Otis Barton loved the ocean and dreamed of seeing the deep. He even invented a wood helmet with glass windows, enlisting the help of a friend to pump air into the helmet with a bike pump so that Otis could explore the harbor. Years later, Otis, an engineering student, teamed up with Will Beebe, the director of research at the Bronx Zoo. Beebe was intrigued by the deep ocean after diving off the Galápagos Islands, and Otis believed he could help him develop a diving tank. The resulting Bathysphere, a 5,000-lb hollow metal sphere with small windows, was barely big enough to fit the two men. They crawled inside and were lowered a terrifying 800 feet into the ocean. They persevered despite a leaky window, claustrophobia, and the constant threat of death by pressurized water if the hatch bolts were to break. The dramatic narrative, illustrated with pen-and-ink and watercolors, culminates in a double- fold-out wordless page spread showing the Bathysphere as a tiny light shining in in the midst of the vast ocean depths. (Ages 7–11)