The suit’s mesh material doesn’t cling like a wetsuit. It also isn’t bulky like a typical drysuit. It’s so light and flexible I can’t imagine how it will provide any thermal protection. Nelinha tells me it’s a nemonium weave. The texture feels more like a cashmere sweater than metal.

The air tanks are impossibly small and compact, no larger than a school backpack. Instead of fins, we have boots with squid-inspired jet propulsion (naturally).

The helmets are the most disconcerting part of the gear. The transparent spheres are made of the same pseudo-glass as the windows on the bridge. When I put mine on, I can breathe just fine. I have a great range of vision. But I feel like my head’s in a fishbowl that smells like…well, a fishbowl.

Gem stands. He looks strange without his holsters, like his hips have suddenly gotten narrower. “May I?”

His voice comes through loud and clear in my stereophonic fishbowl. We check each other’s gear, looking for tears, snags, loose connectors. We shoulder the toolkits Nelinha gave us. Finally, there’s no more reason for delay.

“Okay, Nelinha,” I say. “Flood the airlock.”

It happens in the time it takes Gem to hum one chorus of “Someone Like You,” which he seems to do unironically. We stand in the murky green water, waiting to see if our gear malfunctions. Better here than once we open the exterior lock and get exposed to the pressure of ten atmospheres.

Nothing leaks. I can breathe normally. The suit feels warm, dry, and comfy—so much so that I resent all the hours I spent training in uncomfortable neoprene.

Gem gives me the okay sign—the universal diver’s signal that means, you guessed it, okay.

The moment of truth.

“Nautilus,” I say. “I’m going to leave the ship for a while. We need to inspect the hull.”

I half expect her to respond like an overprotective parent. And what time will you be home, young lady?

I pull the release latch. The exterior door irises open with no problem.

I barely feel the pressure equalize: a tightening in the fabric of my suit, a soft pop in my ears. I curl my toes, the way Nelinha instructed us, and my jet-boots shoot me into the deep.

“Hey, wait up!” Gem’s voice rings in my helmet.

The sound that escapes my throat is somewhere between a laugh and a roller-coaster scream. I’ve gone diving hundreds of times, but it’s never been this exhilarating. I can move effortlessly. There’s no breathing apparatus stuck in my mouth. I turn and rocket in a different direction, scattering a school of bluefin tuna. “This is incredible!”

Gem is laughing, too. He jets past on my left, his helmet glowing like a phosphorescent jellyfish. He tucks his knees and somersaults into the dark.

“Okay, you two,” Nelinha’s voice chides. “You’ve got work to do out there.”

“Aw, but, Mom…” Gem says.

“Don’t start with me, Twain,” she warns, “or I’ll take away your SIG Sauers. Now, if you’ll both please make your way toward the aft of the sub.”