Thanks to the discovery of a book called “Deep,” while it was below zero here in Kansas, I was immersed below sea level in a warm and magical aquatic world where the rules of life are tweaked and a different language is spoken. Hundreds of feet down and more, they speak of chemosynthetic life in the Garden of Eden. Static apnea. Xenophyophores.

In “Deep,” author James Nestor describes diving with sperm whales — without scuba gear — eye to eye for as long as he could hold his breath. Which, in his case, is a long time. The whales (“the biggest predators on earth,” he can’t resist saying) didn’t mind. I found the whole thing ineffably appealing.

The more Nestor described it, the more interesting it got. The massive whales charged the divers, then pulled up short. Nestor heard — and felt — a constant clicking as the whales used echolocation bursts to check him out, increasing in intensity from gas stove sparker to jackhammer on pavement. I later found a similar story in Julia Whitty’s book “[Deep Blue Home][2].”

I was once “clicked” by dolphins, though I didn’t realize it until later when my family excitedly told me they saw them swimming around me. I can hardly imagine swimming in the deep ocean as whales approach — and feeling the clicks of the loudest animal in the world reverberate through me.

The communications of sperm whales are but a piece of “Deep,” expertly embedded in a longer story of, as the subtitle says, “freediving, renegade science, and what the ocean tells us about ourselves.” The book starts with freediving, which I knew nothing about and now find nearly as interesting as talking whales.

As you might guess, freediving is diving without mechanical assistance. I like the idea because divers have learned tricks to overcome inner-ear pressure and extend one’s breath-holding abilities. Also, feeling gravity overcoming buoyancy at the “doorway to the deep,” around 40 feet down, must be pretty cool. Not without serious risks, freediving is now a global competitive sport.

We have learned some amazing things about the human body from freediving. One interesting phenomenon is the mammalian dive reflex, which changes our physiology and allows us to withstand the literal pressures of diving. Blood moves from the extremities to the core. The heart rate drops. The lungs shrink. But the really intriguing lessons, I think, are elsewhere. Freediving offers a chance to experience the world in an entirely new way.

Many whales tend to shy away from submersible vehicles and even the noises of scuba gear. As more is learned about their echolocation abilities, it’s easy to see why. Thanks to modern technology, the rapid-fire streams of sperm whale clicks have been broken down to discrete millisecond clicks, and they’re not random. They can be repeated down to the micro-click, directed at particular individuals, and even called back by other whales. Verbatim, if that’s the right word, over 1500 clicks per second.

Nestor profiles an amateur scientist who’s recording and analyzing these cetacean communications, a sailor who had a close encounter with a pod of whales that changed his life. After finding himself unexpectedly surrounded by curious and clicking sperm whales, Fabrice Schnoller set up a nonprofit research organization called DareWin to study whale and dolphin communication. Nestor more recently has followed suit, with an organization called CETI — the Cetacean Echolocation Translation Initiative.

“Deep” goes on to include more underwater surprises, from coral synchronously spawning under a full moon (how do they know?), to the weird organisms that inhabit the deepest trenches, to the very origins of life — which was perhaps not in tide pools, but near thermal vents at the bottom of the sea.

All in all, this was one of the most engrossing books I’ve read lately. The next time you’re holed up by the Kansas winters, expand your horizons down. Go “Deep.”

• Jake Vail is an information services assistant at the Lawrence Public Library.

[2]: https://lawrence.bibliocommons.com/item/show/70563119