After graduating from high school, Phibs and her four closest friends, a.k.a. the Salt Squad, are on one final epic dive together off the coast of Australia. But when they surface from an underwater cave believed to be filled with treasure, their lives—and the secrets they’ve been keeping—are in danger. Here, Rachel Reiss discusses her inspiration for the story, the research she poured into it, and how her own remarkable scuba diving experiences informed and elevated her debut novel.

Katie O'Connor: Out of Air has a little bit of everything—mystery, adventure, romance, treasure, and even the supernatural. What was your originating idea for this story?

Rachel Reiss: I’m a scuba diver and wanted to tell a story that takes place in that world. Scuba lends itself to so many aspects inherent in a thriller—claustrophobia, pressure, the ocean’s unpredictable conditions, as well as its otherworldly creatures. I wanted to explore all of that, mixed in a story that follows a group of five teens that are in a transformative period in their lives: right after high school. Unlike most stories about discovering buried treasures, I thought it would be fun to play with the idea that maybe some treasures are better left unfound.

This novel is set in such a unique locale. What type of research did you do for Out of Air?

I have gone diving in many remote locations around the world, but on one dive inside a cave in Palau, we surfaced in an air pocket. That was such a surreal experience, being able to breath in a cavern below the surface, and that experience became the catalyst of this story. My husband is an award-winning underwater photographer, which is one of the main character’s hobbies and an integral part of the plot. I also spent months researching various marine creatures and learned a lot of fascinating facts (many of which are in the book!).

Which character on the Salt Squad resonates with you the most?

The five main characters are all very different, and pieces of each of them resonate with me. Some of them wrestle with what their future will look like or if they can defy expectations placed on them, and the main character, Phibs, questions if she can pursue her interest in photography in a world where AI is so prevalent. While the friend group has an undeniable bond, they’re also riddled with distrust over an event that happened in the past, which links up with the present.

You’re an experienced scuba diver yourself. What has been your coolest underwater encounter?

I’ve been fortunate to have some really incredible experiences underwater. I’ve swum with a school of golden rays in the Galapagos (on my birthday!), dove shipwrecks in the South Pacific, and plunged into the Blue Hole in Belize. Diving alongside big pelagic life like manta rays and sharks has been absolutely thrilling, but many of my favorite experiences have been spotting tiny macro life, like colorful mandarin fish hiding in the shallows, and pygmy seahorses the size of lentil beans. Seeing how the ecosystem is all interconnected and how the creatures rely on each other for survival is my favorite thing about diving.