Into the abyss: an ocean scientist plunges to the seafloor in search of secret worlds.

You can't be claustrophobic if you want a career like Susan Humphris's. To commute to her work site, Humphris, another researcher, and a pilot stuff themselves into a metal sphere only 1.8 meters (6 feet) in diameter. "It's very. cramped inside," Humphris says. Once the hatch above her head is tightly sealed, Humphris knows that she won't see daylight for another eight hours.

As a marine geologist at the Woods Hole Oceanographic Institution in Massachusetts, Humphris often works aboard a submersible named Alvin. She rides the underwater vehicle down to the bottom of the ocean where she studies the rocks on the seafloor. During Alvin's two-hour dive to the ocean's depths, Humphris saves battery power by turning off all of the submersible's equipment except a tiny light inside the sphere. The dim glow doesn't even begin to fight the pitch-black gloom of the deep ocean.

Experiencing this long stretch of darkness can be nerve-racking. "On my first dive, I was a little apprehensive," she says.

But once Humphris reached her destination, her nervousness vanished. Peering through a 30 centimeter (12 inch) porthole, Humphris spied a hydrothermal vent. These springs on the seafloor spew out water that has been heated to searing temperatures by volcanic activity beneath Earth's surface. "It was exhilarating seeing this black fluid that looks like smoke gushing out of the seafloor," she says.

OCEAN EXPLORER

Growing up in England, Humphris never imagined that she would do research at 3,600 meters (11,811 feet) beneath the ocean's surface. "I just knew that I wanted a job that involved field work," she says. When she read about the science of marine geology, the photos of scientists aboard ships and submersibles grabbed her attention.

An additional appeal of studying the minerals and rocks on the ocean floor was that so little was known about them. Although 71 percent of Earth's surface is made up of ocean floor, "we probably know less about it than we know about the surface of the moon," says Humphris. Now she is one of a group of scientists who board submersibles like Alvin to study Earth's seafloor.

UNDERWATER RICHES

On a typical research trip, Humphris spends three to five weeks aboard a ship in the middle of the ocean. Periodically during the cruise, she hops into Alvin to work beneath the ocean surface. Between dives, Humphris stays busy in the ship's lab analyzing rock samples that she's collected from the seafloor using Alvin 's electronic arm.

One goal of her research is to learn how deposits of valuable minerals form. Many of the mineral deposits that have been mined on land formed in underwater spots like hydrothermal vents. The fluids that spew out of the vents are packed with minerals and metals including copper. When the fluids hit the chilly seawater, minerals containing these metals precipitate, and the newly formed solids fall onto the seafloor.

Although Humphris's specialty is studying the chemical reactions that form these mineral deposits, her research has exposed her to many different types of science. For instance, there are unique organisms that thrive around the mineral-rich fluids that flow from hydrothermal vents. "The biology is quite spectacular," she says.

Did You Know?

* When Susan Humphris was in graduate school in the late 1970s, hydrothermal vents had not been discovered yet. However, by studying rock samples from the seafloor, Humphris and other scientists speculated that a feature like the vents must exist. Examination of the rock samples suggested that the rocks had reacted with seawater at very high temperatures. In 1977, a team of geologists found the first hydrothermal vent near the Galapagos Islands in the Pacific Ocean.

* In 1986, Humphris was part of the research team that discovered the first hydrothermal vent in the Atlantic Ocean. It was found along the Mid-Atlantic Ridge, a volcanic mountain range that splits the Atlantic Ocean from north to south.

RELATED ARTICLE: Christina Smith.

FUTURE OCEANOGRAPHER

Christina became curious about the ocean after listening to her dad talk about his scuba-diving experiences. "I wanted to see what was out in the ocean that my dad loves so much," says the 17-year-old from California. So last summer, Christina joined a group of high school students and took part in the Oceanography of the Southern Bight, a program studying marine environments off the coast of Southern California.

For a week and a half, Christina took classes and explored the shores along Catalina Island. Then she climbed aboard the SSV Robert C. Seamans, a 134-foot sailboat, and set sail for the Pacific Ocean.

Aboard the ship, Christina helped to deploy scientific equipment and took samples of the ocean water, seafloor, and organisms in the water. "It really drove home the understanding of oceanography and how all the different parts of the ocean relate," she says. Christina is now considering studying marine biology in college. "Without the program, I never would have explored my interest in the ocean," she says. "Now I am considering it as a possible career."

RESOURCES

* To learn more about careers in the marine sciences, visit this site from the Sea Grant program: http://marinecareers.net/

* Get a close-up view of Alvin and go on a virtual expedition at: www.ocean.udel.edu/extreme2001/mission/alvin/

* Students can explore hydrothermal vents at this site: http://Iostcity.jason.org/kids_corner.aspx

web extra

Follow along with ocean research expeditions at: www.divediscover.whoi.edu