By Gabino Iglesias

Jill Heinerth’s Into the Planet starts with the world-renowned cave diver almost dying while being one of the first humans to search for caves inside the B-15 iceberg, the largest moving object on earth.

“How does a dying person know when it’s over? They say your life flashes before your eyes, but that isn’t happening to me now. All I can think about is escaping from the water that I love more than anything else. I’ve spent my life immersed in a relationship with this element that nourishes and destroys, buoys and drowns — that has both freed me and taken the lives of my friends. Now, I have come to my moment of reckoning. My life began in water, and I refuse to accept that it may end here.”

The opening pages are full of tension, adventure, and survival. They set the tone perfectly for what is a superb, honest, incredibly engaging book about Heinerth’s life as a one of the world’s top cave divers.

Heinerth’s resume as a cave diver includes important exploratory dives around the globe, work on expeditions for National Geographic, PBS, and the BBC, and consulting for movies for director James Cameron, among others. And she also has a knack for storytelling.

The writing in Into the Planet is immersive — Heinerth walks a fine line between chronicling the stunning beauty of some of the most exotic locales in the world and the somber realities of her work — like the incredible amount of training and effort that goes into it. She is also honest about the dangers of her chosen profession, which is something she establishes in the book’s opening line: “If I die, it will be in the most glorious place nobody has ever seen.”

While Into the Planet is a book about cave diving full of adventure and danger, it is a biography at the core. Heinerth takes readers along on an amazing journey that starts in an unlikely place: with her working in an office and taking a few diving classes as a hobby. From there, the narrative follows her as she becomes one of the most recognized names in her field. The journey isn’t easy, but the author does a fantastic job of relating everything with ease and using a clear, straightforward prose that makes the book feel more like a conversation with a friend than a biography.

Patriarchy is everywhere, and cave diving is no different. While female explorers are not new, women have been historically underrepresented in exploration. This book shows how wrong that is. Heinerth never preaches against sexism in cave diving, but her writing makes it clear that she was aware of what her gender meant in the context of such a physical, hazardous sport from the start. Instead of letting that be an obstacle, she used it to feed the fire in her belly:

“As the day wore on, though, my pack seemed to grow heavier, and by the time we reached the canyon floor, my toenails had paid the price of jamming up against the ends of my too-snug boots. They were bruised and falling out, and within the next few days, most of them would be gone. It was excruciatingly painful, but I couldn’t appear weak to my expedition mates, so I masked the pain, determined to carry on, unflappable. I wanted my new friends to know they could count of me. If I became a burden to the group, unable to pull my own weight, this would be the last I would be invited on a project. Perhaps I felt additional self-imposed pressure as a woman. In the past I had been held back from opportunities because I was a girl.”

Into the Planet offers a very complete, nuanced look at cave diving and everything it entails. Heinerth weaves together her own stories and adventures with details about preparation, travelling, mosquitoes and dangerous fauna, making sure there is food and water during expeditions, equipment failures, and sudden disasters. She also talks about the emotional aspects of cave diving and discusses everything from “post-expedition blues” and floating aimlessly through life after achieving a goal, to the loss of her mentor while diving — and even coming close to death herself while suffering from the bends, feeling she was “a shaken pop bottle waiting to see if the cap was going to get ripped off.”

There is something captivating about humans pushing their physical and psychological limits to explore places no one has been to before in the name of science and knowledge. Into the Planet is a hybrid book that gives readers a lot of that while also being a captivating biography and a love letter to a sport where any small mistake can result in death — and any perfect dive can mean an amazing discovery.