In this story series, National Aquarium experts typically take us to local places to teach us about the animals and plants found there, but for this edition, we've followed one of our own a bit further afield.
When you think of your travel bucket list, where does your imagination take you? To a pristine sandy beach? A sparkling faraway city? A bustling international marketplace? If you are anything like National Aquarium Director of Dive Programs Holly Bourbon, perhaps your passion for animals, travel and adventure will lead you nearly 10,000 miles from home to one of the most unexplored and potentially inhospitable climates on Earth.
Accessible only by specially equipped vessels that typically depart from the resort town of Ushuaia in Tierra del Fuego, Argentina, Antarctica is one of the most remote destinations on our planet. It is the fifth-largest continent and exists entirely of polar desert ice. Along its coastlines, the region's extremely cold, dry climate ranges from a low of 14 degrees Fahrenheit in winter to possible highs of 48 F, during the summer along its coastlines. Interior winter temperatures can dip as low as negative 76 F. Precipitation on Antarctica exists only as snow and, while it is hard to track, scientists believe that only 2 to 4 inches of moisture accumulate per year, making it the driest place on Earth.
Its maritime habitat—which is teeming with life—consists of the convergence of salty ocean water into which freshwater glaciers and ice sheets gradually melt. While increasingly threatened by warming ocean temperatures, the ice surface is and always has been variable, growing in size from about 1 million square miles at the end of summer to about 7 million square miles by winter.
There are no permanent human populations, countries or governing powers on the continent. While as many as seven nations made claim to the region prior to the international Antarctica Treaty of 1959, it belongs to no one and is not owned or managed by any one nation.
Due largely to the difficulty and possible danger of the journey, the erratic and inhospitable climate and conditions once you arrive, and the sheer distance from almost everywhere, few of us will ever see Antarctica. Even fewer will travel with the goal of slinking into the icy cold waters to take a look around under the surface of the foreboding, tumultuous sea.
But for Holly, an expert scuba diver and aquarist who has dedicated so much of her extensive career to witnessing, understanding and supporting marine biodiversity, a trip to Antarctica had been on the to-do list for close to 15 years. A hearty New Englander with experience diving in the chilly waters of the Northeastern U.S., Holly had long dreamed of experiencing this intimidating and remote polar region.
Although she undertook veterinary studies with the goal of becoming a farm vet, a chance opportunity to become New England Aquarium's first-ever penguin intern drew her into the aquatic world. This experience sparked her passion for diving when it became clear that aquarists with scuba certification could interact more directly with the marine species in their care. Between the New England chill and this early exposure to Antarctic species, it is probably no wonder that Holly has had Antarctica on the brain.
Traveling light might be a virtue—but this was not the trip for that. Because the excursion in March 2023, would take flight from late winter in Baltimore, shift to summer highs of about 100 F during a southbound stopover in Buenos Aires, and then plummet back to about 23 F upon arrival in Antarctica, Holly and her companions would need to be ready for a mind-boggling range of temperatures and conditions on land alone.
Scuba divers hoping to submerge into polar water temps need proper state-of-the-art equipment to tolerate extreme conditions and frigid water temperatures as low as 28 F. For Holly, this meant a new dry suit—think of a thick, insulated wet suit substantial enough to prevent icy water passing through to the skin—and special lightweight thermal undergarments designed to allow divers to spend up to about 30 minutes in Antarctic waters. While Holly owned older equipment made to withstand these conditions, changes in dry suit technology made outfitting herself with updated gear a very good idea.
And, because unpredictable weather and ocean conditions could mean days where divers might be in and out of the water and on and off the ship multiple times, redundancy of gear and clothing was encouraged to make sure all passengers had the back-up wardrobe and equipment necessary to stay warm and safe at all times.
Divers were also expected to have ample scuba equipment, including extra masks, gloves, and undergarments, as well as gauges and regulators with special polar set-ups to head off the potentially catastrophic possibility of having a valve or regulator freeze in polar temperatures, leaving an under-prepared diver without adequate air in deep frigid waters.
While not all passengers on Holly's excursion were there to dive, those who were needed extensive experience, certification and specialized dive equipment. Even with decades of diving in diverse conditions and advanced certifications under her dive belt, Holly needed proof of her credentials including that she had completed a minimum of 30 cold water and 50 dry suit dives, as well as a pre-trip skill assessment signed by a certified dive instructor.
Because diving in freezing water is physically demanding, Holly brushed up on her cold-water diving skills by making a trip up to New England in December 2022 to dive in an icy lake with former colleagues. She also took advantage of the National Aquarium's habitats, including eight weeks of dives in our Atlantic Coral Reef exhibit using the equipment she would take to Antarctica to build her dive muscle memory and, finally, a dive in the brook trout exhibit by the Aquarium's Main Entrance—one of the coldest habitats in our buildings.
Upon their arrival in Ushuaia, Holly and her fellow travelers—her husband, Bill Bourbon, and National Aquarium colleague Director of Animal Care and Welfare Dr. Aimee Berliner—boarded the MV Hondius, a 323-foot long, 46-foot wide Polar Class 6 icebreaker ship. The vessel was equipped with stabilizers that would allow passage through the potentially rough waters of the Antarctic, specifically in the waters of the Drake Passage between the southern tip of South America and the western tip of the Antarctic ice sheet that Holly referred to as "a washing machine."
The MV Hondius was equipped with smaller Zodiac boats reserved for divers and snorkelers heading to dive sites. Once out on these inflatable boats, conditions could change from "OK" to "no way" on a dime. Divers might find themselves fully outfitted and poised to fall back into the water only to have an experienced guide suddenly cancel the dive due to the water, wind or weather. While this could result in the frustration of a once-in-a-lifetime dive experience slipping through one's fingers, the elements at hand—including a sometimes dangerous phenomenon known as katabatic winds—made it clear that, while divers traveling to the other side of the world might make plans, Antarctica is always in charge.
Even one of Holly's main motivators for making this trans-global trek—the opportunity to dive near and perhaps touch an iceberg—came with risks. Though massive, icebergs are not fixed objects. Their motion, even if imperceptible, can create gravitational pulls and friction that can pull divers and other objects toward them or downward. It became very important for Holly and her fellow divers to remain alert at all times when diving near the stunning ice walls.
Because of the delicate fragility of the Antarctic region, sustainability of travel aboard the MV Hondius is of the utmost importance. Some of the green technologies employed to ensure minimal impact and emissions include LED lighting, steam heating, biodegradable paints and lubricants, adjustable pitch propellers, shaft generators (instead of diesel), specialized engines that reduce nitrogen oxide, onboard production of fresh water, and flexible power management systems that keep fuel consumption and carbon dioxide emissions low. Onboard waste production is limited through careful planning of consumed resources, recycling and a complete ban of single-use plastics.
In order to honor and respect the polar animals so many aboard the vessel were traveling to see, the owners, crew and guests aboard the MV Hondius carefully adhere to specific wildlife guidelines established to regulate all Antarctic cruise operations, avoiding any disturbance to these diverse species they hoped to encounter.
You might think of it as an icy barren space, but Antarctica's biodiversity is impressive. The region is home to a multitude of rare, endangered and threatened species adapted to surviving there and almost nowhere else. Some of the species Holly experienced up close included gentoo penguins, orcas, chinstrap penguins, icefish, albatross and others specific to this uncharted region.
There is probably nowhere else on our blue planet better for whale watchers, with species ranging from relatively small killer, minke and sei whales passing through in abundance, as well as humpback, sperm, and southern right whales, and massive species including fin and Antarctic blue whales visible in the icy waters. Antarctic blue whales are the largest animals in the world, weighing up to 400,000 pounds—the equivalent of about 33 elephants. Despite their massive size, they almost exclusively eat up to 8,000 pounds of tiny krill shrimp per day. They are also the world's loudest animal with calls that can reach up to 188 decibels—about 45 decibels more than a jet engine—and can be heard for hundreds of miles.
A range of seal species—including crabeater, elephant, leopard, fur, Weddell, and Ross seals—are found in Antarctica. Weddell seals, named for Scottish sailor James Weddell who first entered the adjacent Weddell Sea in 1823, are both cartoonishly cute and top Antarctic predators, existing on a diet of about 22 pounds of prawns, cephalopods, fish and crustaceans per day.
Antarctic penguin species include emperor, king, gentoo, Magellanic, Adelie and macaroni penguins. But for Holly, it might have been the promise of and abundance of rockhopper and African penguins that she first encountered as an intern at New England Aquarium that lured her towards the south pole. King penguins are the second-largest species of penguin in the world. They can weigh up to 35 pounds and are the most aquatic of all penguin species, spending more time at sea than any other. They can dive to depths of more than 300 meters in pursuit of prey and stay underwater for up to nine minutes.
The 33 species of icefish in the Family Channichthyidae are cold-water beings. They do not have hemoglobin which carries oxygen through most living things, so scientists are unsure how they get enough oxygen, but it is likely from the oxygen-rich waters around them. Without hemoglobin, their blood appears whitish, and their heads look a little like a crocodile, so they are sometimes referred to as crocodile icefishes. They have grayish, black or brown bodies, wide pectoral fins, and two dorsal fins that are supported by long, flexible spines. They can grow to about 30 inches and are an integral part of the Antarctic food chain.
Though tiny, Antarctic krill are the backbone of the Antarctic marine food chain. They live and swim in large schools called swarms that can reach densities of 10,000 to 30,000 individual animals per cubic meter, which is convenient for animals like filter-feeding baleen whales—including minke, humpback, fin and blue whales—some of which can consume up to 3,600 kg of krill per day. The krill feed off phytoplankton and also feature prominently in the diets of many species of Antarctic seals, squids, fishes and penguins. On Holly's trip, her group was lucky enough to witness a pod of about 200 lunge-feeding finback whales feeding on Antarctic krill.
If your imagination takes you to a barren, white, frozen landscape when you think of Antarctica, you might be surprised by the striking colors and remarkable biodiversity on display within the Antarctic Circle—all of which make preserving this magical place critical—both in importance and urgency.
According to NASA, Antarctica has shed an average of 150 billion metric tons of ice per year between 2002 and 2023. Lost ice, of course, becomes sea water. Over the same time period, this has amounted to about 3 inches in global sea level rise due to melting ice and thermal expansion of permanently warmer waters. These warming waters in turn create a vicious cycle, continuing to melt more ice and creating sea level rise that is already impacting Americans and people in coastal communities around the world.
So, what is there to be done? According to Holly, the scientists guiding her Antarctic journey were hopeful, but her main takeaway from her time in the Antarctic is simple:
"There is an ability for us to change things. People have to stop looking within themselves and look outside because what people forget is that we are a global community; no matter what you do, there is an impact. Generations from now are going to be impacted by what we are doing right now. We have to remember that."
As for Holly, her next dive will take her to the warm subtropical waters of Misool in remote southern Raja Ampat, Indonesia. Perhaps someday down the line, Holly will answer the siren song of the Arctic.
Stay tuned for more stories in our Aquarium Inside Out series!
Top photo of Holly Bourbon in Antarctica courtesy of Faith Orrins; all other photos courtesy of Holly Bourbon.
Stay close to home with stories and videos about Baltimore's Inner Harbor and how we care for Aquarium animals' teeth, beaks and bills—and then follow us to the literal end of the Earth, to Antarctica.
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