As a world record-breaking cave diver and National Geographic filmmaker, Jill Heinerth has plunged into uncharted depths around the globe, from the icy tunnels of an Antarctic iceberg to the cerulean cenotes of the Yucatán Peninsula. Filled with scientific and adventurous firsts as well as claustrophobia-inducing squeezes, Into the Planet is an earnestly told story of life as a professional underwater explorer. Although she didn’t learn how to dive until her late twenties, from a young age Heinerth felt that water gave her a freedom she’d never known on land. She shares the hard-earned euphoria of “swimming through the veins of Mother Earth,” but also the terrifyingly narrow margins for error, as she recounts her own close calls and death after death of colleagues and friends. With the hiss and click of a rebreather, Planet submerges the reader between blackness and light, pausing, every so often, for a heart-stopping view of the sublime wilderness below.