The HMS “Challenger” Expedition: Illuminating Earth’s Darkest Abyss

Deep in The Huntington’s library stacks sit two books bound in dark green cloth, embossed with gold images that look like eerie, calcified bones. Part of the Burndy Library collection, this two-volume set, titled Voyage of the “Challenger”: The Atlantic, contains a preliminary, selective account of findings from the expedition of HMS Challenger, a warship that was modified for scientific research in 1872. The expedition’s sole mandate was to circumnavigate the globe to study the mysterious depths of the sea. The findings of the Challenger team are considered the foundation of modern oceanography and continue to inform marine biology and climate change studies to this day. The expedition also presents an extraordinary example of the synergy among art, craft, and science.

The Challenger’s chief scientist, Sir Charles Wyville Thomson (1830–1882), a Scottish marine biologist and professor of natural history at the University of Edinburgh, handpicked his core science team, known on board as “the Scientifics”: an artist/illustrator, three naturalists, and a chemist. Under Thomson’s keen direction, these five men collaborated with skilled sailors, instrument makers, letterpress printers, photographers, printmakers, and visually savvy geologists, among many others, whose craftsmanship and artistry were integral to the entire scientific endeavor.

The Challenger’s mission had two distinct phases: one on water and one on land.

For roughly three and a half years, from 1872 to 1876, the ship sailed 68,890 nautical miles across the Atlantic, Pacific, and Southern oceans, as well as the Antarctic Circle. Using specially designed tools, the Scientifics and sailors conducted deep-sea soundings (depth measurements) and recorded water temperatures, currents, salinity, and weather patterns. They trawled and dredged the ocean floor to collect soil samples and marine organisms—seemingly everything except whales and shipwrecks. The ship’s cannons were removed to create spaces for artistic and scientific work: an onboard zoology lab, a chemical lab, a chart room, and a darkroom for developing photographs.

On land, the Challenger offices in Edinburgh served as the next central hub. The process of examining, sifting through, analyzing, interpreting, illustrating, and—throughout it all—publishing the gargantuan amount of collected data lasted for nearly two decades.

The Huntington’s two preliminary gold-flecked volumes are handheld beach reads compared to the voyage’s final published output. Report on the Scientific Results of the Voyage of HMS Challenger during the Years 1873–1876 spans 50 volumes, each one like a stone slab. Lined up, they call to mind a sobering set of the Encyclopedia Britannica. They don’t have the shelf appeal of the smaller, preliminary versions, but each volume of the complete report contains nearly as much text as full-page illustrations, chromolithographs, photographs, and fold-out maps. For Thomson, the process of publishing his team’s findings—with stunning visual impact—was as important as the data-gathering expedition itself. His core team had expanded to include more than 80 scientists and artists who contributed to the publication, working alongside dedicated craftspeople at the Edinburgh printing house Neill & Company.

One of the most striking volumes, Report on Deep Sea Deposits, was the last one to be published, partly because of its visual complexity. It was co-authored by Alphonse Renard, a Belgian geologist recruited specifically for this report, and Sir John Murray, whose name is now synonymous with modern oceanography. Murray was a student at the University of Edinburgh when he was selected to be a Scientific on board the Challenger, and he later became director of the publication project after Thomson’s untimely death. Murray and Renard leveraged new techniques to analyze and illustrate their findings.

Using microscopic petrography, they placed thin slices of sediment samples under the illumination of a microscope and observed colors, contours, and mineral composition with unprecedented clarity. The images in Deep Sea Deposits are chromolithographs based on hand-drawn illustrations: With one eye on the microscope and one hand at the ready, the illustrator-geologist shifted his gaze intently and rapidly from lens to paper to render the fine details observed in each sample. This was no small feat of eye-hand coordination, and it enabled intricate geologic analysis.

Before the Challenger reports, knowledge of the world’s vast ocean environments—let alone their bottommost depths—was patchy at best. Yet it was increasingly important to the British government, which funded the Challenger voyage. Britain’s new international communication systems relied on telegraph cables that crisscrossed the ocean floor. These thick but precious cables were dropped onto poorly mapped underwater plains, valleys, and mountain ranges, where they functioned out of sight.

Murray and Renaud created the world’s first comprehensive geologic map of the ocean floor. Color-coded zones were defined by such sediment types as red clay, blue muds, or globigerina ooze—a mud formed from decomposing plankton. The Challenger team also identified what they called “cosmic spherules,” which were composed of magnetic particles rich in heavy metals. In Deep Sea Deposits, this space dust was illustrated using shimmering gold and silver inks. Now known as micrometeorites, the particles were an unexpected link between the seafloor and deep space.

The Challenger’s Scientifics were keen to settle the debate about “life-zero”: Was there a limit underwater where intense pressure, darkness, and frigid temperatures made it impossible for marine life to survive? Some scientists thought the limit was 300 fathoms (roughly 1,800 feet). A few years before he oversaw the Challenger expedition, Thomson pushed this limit to 650 fathoms—and then 2,000. Challenger’s deepest sounding was 4,475 fathoms in the western Pacific, in what is now known as the Mariana Trench, the deepest known ocean trench on the planet.

The Challenger overwhelmingly proved that life exists in all the oceans’ abysses. Of the final Report’s 50 volumes, two are dedicated to botany and 40 to zoology. The Report’s contributors described plankton, sea cucumbers, corals, sharks, octopuses, kelp, fish, and marine mammals of all sizes. Rich visual detail was central to these volumes. The lead artist on board the Challenger, John James Wild, was so highly valued that he earned twice the annual salary of the other Scientifics (only Thomson himself earned more). Later, during the publication process, lithographers, engravers, and illustrators continued to create and print images of more than 100,000 collected specimens. A well-known German naturalist and artist, Ernst Haeckel lent his skills to the reports on plankton and medusae (jellyfish).

Before HMS Challenger set sail, visualizations of the deep sea and marine life elicited wonder, anxiety, and curiosity about an unseeable “beyond”—similar to how later generations imagined deep space exploration. In many ways, the underwater world that the Challenger publications brought to life on the page was even stranger than fiction. Yet today, the Report’s unprecedented, visually rich dataset continues to be referenced by oceanographers and marine scientists. It provides an increasingly useful baseline for understanding the current conditions of our planet’s largest ecosystem and its potential futures. The urgency of this work is underscored by one of the United Nations Sustainable Development Goals dedicated solely to “Life Below Water.”

The Huntington’s complete set of reports is something of a rarity: Only 750 sets were printed because of the care and craftsmanship of their production, and many sets today are incomplete. Each volume of the set is an invaluable artifact of scientific and artistic collaboration.

Related links:

• HMS Challenger Collections
• University of Edinburgh Exhibitions: “Sea Change”
• Oceans 1876 Portal: Challenger Expedition
• Royal Museums Greenwich: “HMS Challenger”

Natalie Lawler is an assistant curator of special projects at The Huntington.