National Geographic News
A photo of Nereus, a research submarine.

The deep-sea research vehicle Nereus, owned and operated by the Woods Hole Oceanographic Institution, was one of a kind.

PHOTOGRAPH BY ADVANCED IMAGING AND VISUALIZATION LAB, WOODS HOLE OCEANOGRAPHIC INSTITUTION

Jane J. Lee

National Geographic

Published May 12, 2014

On Friday a deep-sea robotic vehicle named Nereus vanished under the weight of 6.2 miles (9,977 meters) of water in the western Pacific Ocean.

Surface debris—spotted the day after researchers on a support ship lost contact with the vehicle—suggested Nereus suffered a catastrophic implosion while exploring the Kermadec Trench northeast of New Zealand.

Owned and operated by the Woods Hole Oceanographic Institution (WHOI) in Woods Hole, Massachusetts, Nereus was the only scientific vehicle currently operating that could work at such extreme depths. Its loss has "certainly put a big rent in the works here," says Susan Avery, president and director of WHOI.

Nereus was lost 30 days into a 40-day expedition to explore the second deepest trench in the world. Scientists plan to finish their research trip with the remaining tools available to them, including baited traps, an underwater elevator, and other instruments they can send over the side of the ship and subsequently recover.

Nereus was also scheduled for five or six more expeditions later this year, Avery says. Now, all of those projects will have to go back to the drawing board to see what can be salvaged from this loss.

Shattered Remains

Researchers on Nereus's support ship, the R.V. Thomas G. Thompson, had just used the vehicle to collect a sea cucumber on May 9 when their camera feeds went dark. This had happened before, WHOI spokesperson Ken Kostel wrote in a statement, and operators on the ship weren't particularly worried.

Then they also lost touch with a positioning system on Nereus that kept track of the vehicle's location in relation to the ship. Under such circumstances, the robot was programmed to wait a half hour so that the ship could be moved a safe distance away from its last known location, then drop the weights keeping it at the bottom so that it could surface.

Expedition members on the ship had waited for signs of their vehicle for almost 24 hours, when the crew spotted chunks of plastic in the water. When they brought the plastic onboard, "it was without a doubt pieces of Nereus," wrote expedition leader Casey Machado on WHOI's Facebook page.

Out With a Bang

Scientists speculate that a portion of their robot imploded under the immense pressures—about 16,000 pounds per square inch—in the ocean depths.

Certain parts of an underwater vehicle like Nereus, such as sensitive electronics, must be kept at the same pressure they'd experience at sea level, says Steve Etchemendy, director of marine operations at the Monterey Bay Aquarium Research Institute (MBARI) in California. He is in charge of the research organization's ships, remotely operated vehicles (ROVs), and autonomous underwater vehicles (AUVs).

If those parts of the vehicle fail and experience uncontrolled pressure changes, "it's like sticks of dynamite going off," Etchemendy says.

The loss of the exploration vehicle won't be easy to overcome, WHOI's Avery says. Nereus was an $8 million investment and it was one of a kind, she says. Movie director James Cameron's submersible DEEPSEA CHALLENGER can dive to 33,000 feet (10,000 meters), but it can't do so with the regularity needed for the kind of scientific research WHOI conducts, she says.

"This is a tragic loss for deep science," Cameron wrote in a statement posted to WHOI's Facebook page. He called for an evaluation of the nation's ability to explore the deep sea—and lamented how the loss of Nereus will affect access to "the last great frontier for exploration on our planet."

Follow Jane J. Lee on Twitter.

18 comments
Brian Kelly
Brian Kelly

 Funny first sentence IMO, 

"A catastrophic implosion likely led to the loss of the only scientific vehicle that could work at such extreme depths."    Obviously it did not "work at such depths.  Nice try though.

Victor Bender
Victor Bender

In oceanographic work the understanding is if you can't accept losing the equipment don't put it into the water. AUV's and other non person carrying vessels use glass balls for their flotation. Glass is lighter and for the most part stronger that many other materials, yet when it fails it implodes. Weight is important when trying to balance useful load vs. vehicle weight. This makes for a tightrope of technological decisions. Exploration costs money. Exploration also produces results. If we didn't explore either inner or outer space we wouldn't even be on the computer reading and writing comments etc, etc, etc.

Brant Baun
Brant Baun

Look at the subtitle of this article:

"A catastrophic implosion likely led to the loss of the only scientific vehicle that could work at such extreme depths."

Since it imploded, that means it COULD NOT work at the extreme depths!

There goes millions of taxpayer money. 

james crawford
james crawford

don't think it was shot down by and alien craft, they are down there!!

Fra Rei
Fra Rei

All that money and technology yet the failure to put in a backup flotation device.

albert stapf
albert stapf

They said this is the second deepest. Fourth paragraph first line.

Isaac Queral
Isaac Queral

Isn't the Marianas Trench the deepest?  This must be a new discovery.

Alan Barlow
Alan Barlow

@Brant Baun 

EVERYTHING fails eventually, from toasters to lawmowers to automobiles to Mars Rovers. Put your thinking cap on. Like everything  else, IT WORKED UNTIL IT FAILED. Now put your dunce cap on. 

mike Shepard
mike Shepard

@Brant Baun  

At 8 million dollars the Nereus was still 13 million dollars cheaper than a single Black Hawk helicopter and the US military has bought thousands of those. Keep in mind that we are talking about 20 times the operating depth of a seawolf class submarine. When a pressure vessel fails at 16,000 psi there is a shock wave that destroys the rest of the vehicle. So extra flotation is irrelevant.


The Nereus conducted research in an extreme environment inaccessible to almost any other vehicle for almost 5 years. It was 8 million well spent. (It wasn't even all government money.)

mike Shepard
mike Shepard

@Brant Baun  At the cost of only 8 million dollars it is 13 million dollars cheaper then a single Black Hawk helicopter. The US military has bought many thousands of those. The Nereus conducted research in an environment almost no other vehicle can tolerate for almost 5 years. Keep in mind that this is 20 times the operational depth of a military submarine. Failure of a pressure vessel at that depth causes a shockwave that would destroy the vehicle completely. Extra flotation would be irrelevant. 


It was 8 million well spent.  (It wasn't even all government money)

Todd Brown
Todd Brown

@Brant Baun You really are nit-picking, if you buy a new car and drive it 100,000 miles and then the engine throws a rod while driving down the highway, would you say that the car was not ever capable of driving on the highway?

How old is your refrigerator and why did you get the one you currently have?  Did you wake up one day to find the inside temperature the same as the outside?  By your reasoning it could not hold temperature.

Things work until they don't work anymore.

Justin L.
Justin L.

@Brant Baun  So you're opposed to the National Science Foundation funding scientific research?  Maybe we should just abandon science altogether and demand the government spend our tax dollars on things that don't advance our civilization...

Victor Bender
Victor Bender

Backup flotation at that depth? Sounds like a good idea. Any guesses how?

Patty Brown
Patty Brown

@Fra Rei  Completely clueless.  Not much of a physics / engineering type, I guess...  

john roberts
john roberts

Chuckle..... Aptly spewed like those who criticize the bread without a clue as to how one bakes the loaf.... Study physics and then invent the device that's going to maintain form and function after collapse and loss of submersible integrity at 16,000psi

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