National Geographic

DEEPSEA CHALLENGE

Expedition Risks and Dangers

Editor’s note: On March 26, 2012, James Cameron made a record-breaking solo dive to the Earth’s deepest point, successfully piloting the DEEPSEA CHALLENGER nearly 7 seven miles (11 kilometers) to the Challenger Deep in the Mariana Trench. DEEPSEA CHALLENGE is now in its second phase—scientific analysis of the expedition’s findings. Click here for news about the historic dive, an exclusive postdive interview with Cameron, and information about the next phase of the expedition.

“Worry is a good thing when you’re an explorer. It’s when you’re cavalier, when you take risk for granted, that’s when you’re gonna get bit.”
— James Cameron

Exploration is inherently dangerous. The DEEPSEA CHALLENGE team is cognizant of the risk of traveling to the ocean’s deepest point and does everything possible to mitigate the many hazards. Under the leadership of James Cameron and Ron Allum, each and every member of the team is encouraged, even required, to be explicit about the risks that are simply part of their work. The expedition philosophy follows the thinking that the only way to protect against risk is by anticipating, understanding, and addressing it outright. There is a great deal to be gained if DEEPSEA CHALLENGE is successful, but all members of the expedition acknowledge that lives are at stake and that, as Cameron himself has written, “there are a lot of ways to die.”

Cameron outlines some of these ways, in his own words, below.

IMPLOSION
The obvious one. You’ve miscalculated the design of your sphere. As you approach the bottom, with barely a warning groan, the sphere buckles suddenly. Faster than you can scream, you’re smashed into jam.

PENETRATOR FAILURE
There’s a dead short someplace and one of the pins in your electrical penetrator—the device that feeds power and control signals through the sphere wall—melts, causing the penetrator to fail. The water jet erodes the interior of the penetrator, allowing seawater to blast inside, at 16,000 psi.

FREEZING
If you get stuck on the bottom your weights don’t drop, and it’s a race between your life support running out and freezing to death. But you’ve got 60 hours of scrubber and O2, so freezing wins. Because the water outside is just above 0°C … icewater.

FIRE
Electrical fires can break out among all of the sub’s gadgets, and with O2 pumping into the pilot sphere, fires can grow quickly. Although a fire extinguisher is stored in the sphere, it may not be enough to extinguish a sizable fire.

VIEWPORT FAILURE
You’re looking out the viewport when suddenly you see cracks developing. The cracks quickly web throughout the thick volume of the acrylic, and it starts to give way. Then BANG! The cork pops and the sea hammers in like a supersonic piston.

ADRIFT
Only one ascent weight drops instead of both. So you ascend close to the surface but not all the way. Over the next ten hours a two-knot midwater current takes you 20 miles away, and the surface crew has no idea where you are, because you’re not at the surface.

Three Unexpected Dangers of Deep-Ocean Exploration

The “behind the scenes” information posted on the DEEPSEA CHALLENGE website provides incredible insight into the types of challenges—and logistics—that go into planning and executing an expedition of this size and scope. There are surprises everywhere—things one might never have thought to consider on their own and the planning for which there are few, if any, precedents. The work of the DEEPSEA CHALLENGE is an exercise for mystery and puzzle-loving minds. Three expedition risks that the DEEPSEA CHALLENGE team has anticipated and addressed that might take nondivers by surprise are listed below.

HYDROTHERMAL VENT-INDUCED MELTDOWN
As first reported in expedition blogger Dr. Joe MacInnis’s March 18 entry, several of the expedition’s members, including the legendary Captain Don Walsh, one of two people ever to have been to the Challenger Deep prior to this expedition, discussed the risks of “flying a research sub too close to a hydrothermal vent,” where they “casually mention[ed]” that the water temperature approached 700 degrees and would melt a sub’s viewport.

SEAFLOOR COMMUNICATIONS CABLE ENTANGLEMENT
Submarine communications cables are cables that traverse the seafloor between land-based stations to extend telecommunication signals across stretches of ocean. Were the sub to become entangled in these cables, it might prevent it from returning to the surface.

HYPOTHERMIA AND HYPERTHERMIA
The DEEPSEA CHALLENGER submersible is a state-of-the-art vehicle—but it is not equipped with a thermostat that can adjust internal temperatures for comfort. The temperature range for a dive borders on the extreme. As the National Geographic expedition website reports, “the temperature will drop from sauna-like at the surface to meat-locker cold at the bottom.” Cameron will dive wearing many layers but the risk of overheating or freezing is significant. In a personal communication to his team, Cameron described a recent experience with heatstroke-like symptoms as he waited inside the sub’s unventilated pilot sphere to be launched into the ocean:

“Hyperthermia early in the dive (and throughout shallow test dives) is a hazard in this vehicle, at least as much as hypothermia late in a deep dive. I found my mental performance slipping after two hours at 102 degrees/100% humidity [while piloting the sub for a test dive]. It doesn’t sound that hot but with zero evaporative cooling available in such a tiny airspace, I’m sure my core temp was going up to match air temp. I got sub internal temp back down to 97 degrees. But by then I was trashed, and had lost several pounds in water.”

Science Partners

  • Additional major support provided by The Alfred P. Sloan Foundation
  • NASA Jet Propulsion Laboratory
  • Scripps Institution of Oceanography, UC San Diego
  • University of Hawaii at Manoa
  • University of Guam