Swimming in the wake of mentor and longtime National Geographic Explorer-in-Residence Sylvia Earle, marine biologist Tierney Thys is the next generation's champion of ocean exploration. "Every time you step off the land into the liquid—into the ocean—you're traveling somewhere very few people venture. You've immediately embarked on a great adventure," she says.

Since 2000, Thys and her colleagues have been traveling the world's oceans to study the giant sunfish (mola). Though these fish can grow more than ten feet long and weigh over 5,000 pounds, little is known about them.

By placing high-tech satellite tags on molas and collecting mola tissue samples for genetic analysis, Thys and her colleagues hope to uncover their secrets: How did they come to occupy all tropical and temperate seas? Where, when, and at what size do they reproduce? How do they locate their jellyfish prey? Are there more ocean sunfish species yet to be discovered?

Thys was born in 1966 in California. As soon as she could walk, her parents slipped her into a homemade wet suit and tossed her into the surf. She has loved the water ever since.

When Thys graduated in 1988 with a degree in biology from Brown University in Rhode Island, she decided to dedicate her career to studying the ocean. Through a mutual friend in California, Thys met Sylvia Earle, who was helping design a winged submarine for ocean exploration.

A certified pilot, Thys was immediately captivated and joined Earle's team. Several years later, Earle wrote Thys a recommendation letter for graduate school at Duke University in North Carolina, where she earned a doctorate in biomechanics in 1998. Her dissertation investigated the mechanics of swimming muscles in fish, and she's been intrigued with the fish form ever since.

"When it comes to fishes, the mola really pushes the boundary of fish form," says Thys. "It seems a somewhat counterintuitive design for plying the waters of the open seas—a rather goofy design—and yet the more I learn about it, the more respect and admiration I have for it."

In addition to publishing research and compiling a book on molas, Thys is the science editor at Sea Studios Foundation, a documentary film company based in Monterey, California. She also worked on a series about Earth system science and global environmental change.

The two careers, Thys says, are complementary: "I hope all aspects of my work can help raise awareness of the oceans—not only of the spectacular life within the boundaryless blue, but also the pivotal role the oceans play in our global climate and the livelihood of humanity."