What’s It Feel Like To Plunge 6.8 Miles Into the Sea?

Answers to your questions about the news.
March 27 2012 7:03 PM

Why Do Deep-Sea Explorers Wear Those Tiny Knit Caps?

The ins and out of submersible travel.

Jacques Cousteau, James Cameron and Steve Zissou wearing skullcaps.
James Cameron, center, emerges from the Deepsea Challenger submersible after his successful solo dive to the Mariana Trench. The dive was part of Deepsea Challenge, a joint scientific expedition by Cameron, the National Geographic Society, and Rolex. At left, marine explorer Jacques Cousteau. At right, Bill Murray as Steve Zissou in The Life Aquatic.

Office of National Marine Sanctuaries, NOAA; Mark Thiessen/National Geographic; IMDB, © Touchstone Pictures.

Director James Cameron successfully completed a 6.8-mile-deep dive to the most remote region of the ocean Sunday and was shown emerging from his submarine in a small knit cap. Jacques Cousteau’s red knit cap was a signature part of his look, which was aped by Bill Murray and his crew in the movie The Life Aquatic With Steve Zissou. Why do underwater explorers wear skullcaps?

Forrest Wickman Forrest Wickman

Forrest Wickman is a Slate staff writer. 

Because it’s practically freezing down there. The water temperature at the bottom of the ocean usually hovers around 37 degrees Fahrenheit, and most deep-sea exploration vehicles don’t have climate control. Explorers tend to bring hats, gloves, long johns, and other warm layers, which they pull on as they descend and the temperature drops. Socks and caps are particularly important, as it’s coldest on the floor and ceiling of the submersible. Because of concerns over electrical fires, deep-sea explorers wear natural fibers like cotton and especially wool, which is fire retardant, instead of synthetic fabrics.

Deep-sea divers have been wearing skullcaps, also known as watch caps or seaman’s caps, since long before the adventures of Jacques Cousteau. He may have picked up the style from hard-hat divers—those 19th-century explorers who wore big copper helmets—who favored red knit caps for decades. The character of Steve Zissou in The Life Aquatic wore an identical cap in homage to Cousteau.

Aside from the extreme temperature, diving in a deep-sea submersible is much like flying in an airplane, except a much tighter squeeze. In order to withstand the crushing pressure of deep waters, the vehicles must be compact and often have spherical cabins. Changing clothes is difficult because there’s rarely enough room to stand. Going to the bathroom, for which there is little privacy, is a particular challenge for female explorers, who have to contort themselves more than men to use the urine-collection bottles. (The bottles come with different attachments for men and women.) While divers may avoid drinking fluids in order to put off urination, they must also be careful not to become dehydrated. For long dives, air can be recycled using carbon dioxide scrubbers and oxygen generators. (Scientists have attempted to develop liquid breathing, the technology used in Cameron’s deep-sea thriller The Abyss. Just as in the movie, mice were able to adjust to breathing the liquid. However, the application of liquid breathing for human diving remains hypothetical.) Still, these technologies can’t always keep up with passengers’ demand for oxygen, and enough carbon dioxide can accumulate to cause headaches. The cabin is pressurized enough that divers will feel little of the extreme pressure outside of the vehicle—dangers like nitrogen narcosis and the bends aren’t a concern in a functioning vehicle—but their ears might pop when the submarine is opened and repressurizes at the surface.

The prospect of deep diving may seem exciting and include moments of thrilling discoveries, but the trip itself is hardly a thrill ride. Vehicles usually travel at a maximum speed of only 2 or 3 miles per hour, so divers sense little of the motion of ascent and descent. Since it can take several hours to reach the seabed, most of the trip can be spent just passing time. Pilots and solo explorers like Cameron must be mindful throughout the journey, but passengers may simply gaze out the porthole (though the water goes dark after about 10 minutes), read, or doze off; some occupy themselves with a computer or music. When resurfacing, however, turbulent waters around the surface can feel like an amusement park ride, or worse, and many craft don’t have seats or seat belts.

Got a question about today’s news? Ask the Explainer.

Explainer thanks Barbara Campbell and Craig Cary of the University of Delaware.

Video Explainer: Why Aren't There More Slam Dunks in Women's Basketball?

This video was produced from an original Explainer by Brian Palmer. Want more questions answered? You can now watch video Explainers at Slate's News Channel  on YouTube.



Talking White

Black people’s disdain for “proper English” and academic achievement is a myth.

Hong Kong’s Protesters Are Ridiculously Polite. That’s What Scares Beijing So Much.

The One Fact About Ebola That Should Calm You: It Spreads Slowly

Operation Backbone

How White Boy Rick, a legendary Detroit cocaine dealer, helped the FBI uncover brazen police corruption.

A Jaw-Dropping Political Ad Aimed at Young Women, Apparently

The XX Factor
Oct. 1 2014 4:05 PM Today in GOP Outreach to Women: You Broads Like Wedding Dresses, Right?

How Even an Old Hipster Can Age Gracefully

On their new albums, Leonard Cohen, Robert Plant, and Loudon Wainwright III show three ways.

How Tattoo Parlors Became the Barber Shops of Hipster Neighborhoods

This Gargantuan Wind Farm in Wyoming Would Be the Hoover Dam of the 21st Century

Oct. 1 2014 8:34 AM This Gargantuan Wind Farm in Wyoming Would Be the Hoover Dam of the 21st Century To undertake a massively ambitious energy project, you don’t need the government anymore.
  News & Politics
Oct. 1 2014 7:26 PM Talking White Black people’s disdain for “proper English” and academic achievement is a myth.
Buy a Small Business
Oct. 1 2014 11:48 PM Inking the Deal Why tattoo parlors are a great small-business bet.
Oct. 1 2014 6:02 PM Facebook Relaxes Its “Real Name” Policy; Drag Queens Celebrate
  Double X
The XX Factor
Oct. 1 2014 5:11 PM Celebrity Feminist Identification Has Reached Peak Meaninglessness
  Slate Plus
Behind the Scenes
Oct. 1 2014 3:24 PM Revelry (and Business) at Mohonk Photos and highlights from Slate’s annual retreat.
Brow Beat
Oct. 1 2014 9:39 PM Tom Cruise Dies Over and Over Again in This Edge of Tomorrow Supercut
Future Tense
Oct. 1 2014 6:59 PM EU’s Next Digital Commissioner Thinks Keeping Nude Celeb Photos in the Cloud Is “Stupid”
  Health & Science
Oct. 1 2014 4:03 PM Does the Earth Really Have a “Hum”? Yes, but probably not the one you’re thinking.
Sports Nut
Oct. 1 2014 5:19 PM Bunt-a-Palooza! How bad was the Kansas City Royals’ bunt-all-the-time strategy in the American League wild-card game?