No Holes Barred

In the pursuit of scientific riches, Abess Center director Kenny Broad leads an extreme expedition of fearless explorers into the legendary blue holes of the Bahamas.


Descending hundreds of feet down a blue hole can be a risky pursuit, from mazes of murky underwater passageways and violently shifting currents to layers of toxic water that burn the sinuses and churn the stomach. For Kenny Broad, though, the lure of these submerged limestone caves, punctuated by miles-long corridors—some barely wide enough to accommodate a human body—is the chance to discover ancient fossils, rare creatures, and scientific treasures that reveal our climatic history.

“You really don’t know what you’re going to find when you go in there,” says Broad, professor of marine affairs and policy at the Rosenstiel School of Marine and Atmospheric Science and director of the Leonard and Jayne Abess Center for Ecosystem Science and Policy. “And that’s the draw.”

Expert diver Kenny Broad, bottom, a marine affairs and policy professor at UM, and his crew conducted around 150 dives in these spectacular environments in the Bahamas funded by the National Geographic Society, the National Museum of the Bahamas, and the National Science Foundation. Above, a diver navigates a vital guideline in Dan's Cave on Abaco Island. This stalagmites, or calcium carbonate formations, found in this city under the sea offer scientists a way to study climate change and other shifts dating back to the ice ages, when the caves were dry.

Blue holes offer scientists a living laboratory with windows into the past and the future. Their complex chemistry includes a thin layer of freshwater atop a dense layer of salt water. As bacteria break down the organic material in these holes, they produce hydrogen sulfide, a toxic gas that gets trapped in layers around 30 feet down. Below this zone, in the salt water, is an oxygen void, resulting in the exquisite preservation of a trove of animal and human bones, some of which date back more than 13,000 years, and otherworldly mineral formations more than 500,000 years old. It’s also where clues are emerging about climate patterns and possible future changes associated with global warming.

“A blue hole is like a time capsule,” says Broad, whose fascination with anthropology came from working as a commercial diver for scientists back in the 1980s. “They tell us what life forms may be like in other inhospitable places. These weird bacteria can live in extreme environments without oxygen, in complete darkness, and in poisonous gases. We can think of them as modern-day analogies to likely conditions on other planets, or to the primordial, ancient oceans that life evolved from here on Earth billions of years ago.”

Researching blue holes provides unparalleled adventure for expert divers like Broad, named a National Geographic Emerging Explorer in 2006 and the 2011 National Geographic Explorer of the Year along with his late colleague, renowned underwater photographer Wes Skiles. But it also requires plenty of specialized equipment and a cool head. “It’s more of an activity for control freaks, computer nerds, and yoga aficionados,” he explains. “Adrenaline is your enemy.”

The dive team makes its way through the North Passage portion of Stargate, a blue hole on Andros Island. A new NSF grant will help Broad and his UM colleagues further their exploration and studies of these hard-to-reach scientific riches.

Divers lay a thin guideline as they thread themselves through tight quarters and fragile stalagmite forests, often coming out in zero visibility. To be ready for any type of technical malfunction, they carry multiple tanks, lights, safety lines, masks, fins, and computers. They often use specialized equipment, called rebreathers, that recycle and filter exhalations, allowing them to go down more than 300 feet deep and stay submerged for up to several hours at a time. They use a mix of breathing gases to avoid oxygen toxicity and nitrogen narcosis, or “rapture of the deep,” a state of impaired judgment caused by pressure acting on inert gases at extreme depths. In this environment, there are no second chances.

Beginning in 2008, Broad launched a scientific expedition to the Bahamas for the National Geographic Society to explore blue holes formed as a result of the fluctuation of the ice ages over millions of years. A Nova-produced film of the expedition aired on PBS in February 2010, followed by a stunning National Geographic cover story that August.

The mission was a perfect fit for the Abess Center, of which Broad became director in 2009. Established in 2002 and named in 2006 with a $5 million gift from the Abesses, the interdisciplinary center draws on UM’s internationally recognized programs in marine science, ecology, architecture, engineering, and environmental law to equip students for careers as environmental scientists, policymakers, and planners. A doctorate in environmental science was recently added to its offerings.

“Blue holes offer so much to so many different scientific disciplines: climate science, biology, archaeology, paleontology, and astrobiology,” explains Broad, whose team conducted 150 dives on Abaco, Andros, and five other Bahamian islands over two months.

In addition to several UM researchers, the crew included noted explorer Brian Kakuk; Nancy Albury, a paleontologist from the National Museum of the Bahamas; David Steadman, a world expert on island extinctions from
Florida Museum of Natural History; Jenn Macalady, an astrobiologist from Penn State University; Tom Iliffe, a cave biologist and explorer from Texas A&M University; several students from UM and the Bahamas; and a film team led by Skiles.

"It's the only time you can have 100 percent concentration, because it's a life or death endeavor," says Broad, National Geographic Explorer of the Year.

Carrying up to 1,000 pounds of gear among them, the divers succeeded in unearthing the remains of native Lucayan tribe members who inhabited the Bahamas over 1,000 years ago, as well as crocodiles and extinct tortoises more than 4,000 years old. They collected bones from a burrowing owl, a Bahamian boa constrictor, and dozens of other species—some new to science—plus bacteria specimens and remipedes, which are tiny crustaceans nearly unchanged for 200 million years.

From deep within the caves, the researchers also gathered dozens of stalagmites. These calcium carbonate formations built up during the ice ages, when sea levels dropped and the sinkholes were dry. For Rosenstiel School professor of marine geology and geophysics Peter Swart, they contain clues to climate changes over tens of thousands of years.

“The stalagmites are solid, with layers that are basically like tree rings related to age, so you can date them,” Swart explains. His theory is that red iron deposits in the stalagmites are remnants of dust that blew across the Atlantic from the African Sahara thousands of years ago. Those massive storms, he says, appear to be connected to “Heinrich events,” super cold snaps of the last glacial period.

These daring blue hole divers are uncovering findings about the origin of life, the evolution of human occupation in the Caribbean, and climate stability. They've discovered everything from living creatures such as this inch-long Agostocaris cave shrimp to a 3,000-year-old Cuban crocodile skull and the centuries-old skull of a Lucayan Indian.

Amy Clement, a Rosenstiel School associate professor of meteorology and physical oceanography, and Monica Arienzo, a marine geology graduate student, are also using the stalagmites to further their climate research. With a microsampling device, Arienzo has evaluated close to 2,000 stalagmite samples, each comprising less than the amount of salt one would sprinkle on a meal, for their carbon and oxygen isotope values.

Clement is using the research to design experiments with a computer model that will simulate the climate from the ancient African dust storm period. Among the questions she’s trying to answer is whether those dust storms may have been linked to ice events and how the dust then affects climate.

“The data indicate that dust from Africa is potentially a powerful climate feedback,” says Clement, who is married to Broad. “This suggests that if the Sahara undergoes changes in the future, the impact could be global.”

Cave diver and underwater photographer Nikita Shiel-Rolle, A.B. ’10, took part in Broad’s expedition as an undergraduate. She is now educating fellow Bahamians about environmental issues and supports her country’s efforts to create a South Abaco Blue Holes Conservation Area. “A lot of these blue holes are in the freshwater lens, and there are a lot of health issues associated with them,” she says. “The blue hole expedition is paramount for our country. For Bahamians to make educated decisions to ensure a sustainable future, we need to understand the connection between the blue holes and the ecosystem.”

Liquid time capsules: Professor Kenny Broad says sea-level rise associated with global warming will change the water chemistry of blue holes such as Dean's Blue Hole, above left, and Sawmill Sink, below. "We're going to lose a lot of valuable information very quickly," he warns, adding that blue holes are also "critical reservoirs of fresh water on a global scale."

Broad, who also serves as co-director of his alma mater Columbia University’s Center for Research on Environmental Decisions, says Bahamian blue holes—often used as dumping grounds and threatened by pollution and sea-level rise—serve as a microcosm for the world’s supply of fresh groundwater. Researching them, he explains, has implications for policy decisions such as water resource management, land use, and zoning.

A devoted educator, Broad con-tinues to keep attention focused on these amazing labyrinths, enthralling standing-room-only lecture halls with lessons and anecdotes about his extreme expeditions and sharing many of the incredible scenes captured by his longtime colleague Skiles, whose photos grace last year’s 22-page National Geographic spread.

Unfortunately, Skiles died during a research dive off of Boynton Beach just days before the issue came out. “He was larger than life,” Broad says of his close friend and mentor. “If you were interested in learning, he would spend all the time in the world with you.”

This summer the two men were honored (Skiles posthumously) as co-recipients of National Geographic’s inaugural Explorer of the Year Award, in recognition of their shared passion for and Broad’s enduring commitment to uncovering hidden worlds for the sake of enlightenment, as well as sharing their indescribable beauty.

“When you dive in a blue hole, you get this feeling that you don’t know what’s around the corner,” says Broad. “You may go through a passage with horrible visibility, and then you turn a corner and you’re in a flow of crystal-clear water that opens up into a spectacular gallery of natural art.”


Ana Maria Lima is a freelance writer based in Miami, Florida.

   Click here to watch the Extreme Cave Diving documentary. Click here for more information on the Abess Center for Ecosystem Science and Policy. Click here to see more photography by Wes C. Skiles.