On December 21, 1872 the H.M.S. Challenger sailed from Portsmouth, England, for an epic voyage which would last almost three and a half years. It was the first expedition organized and funded for a specific scientific purpose: to examine the deep-sea floor and answer questions about the ocean environment.

The expedition covered 69,000 miles (about 130.000 km) and gathered data on currents, water chemistry, temperature, bottom deposits and marine life at 362 oceanographic stations. More than 4700 new species of marine animals were discovered during the course of the voyage, many of which were found on the seafloor – an environment that scientists originally believed to be too inhospitable to support life.

It all began in 1868, with British naturalist William B. Carpenter and Sir Charles Wyville Thomson, Professor of Natural History at Edinburgh University. They persuaded the Royal Society of London to sponsor a prolonged voyage of exploration across the oceans of the globe. But it was not until 1872 that Royal Society of London obtained the use of the HSM Challenger from the Royal Navy. The ship was modified for scientific work with separate laboratories for natural history and chemistry. The cost of expedition was £200,000 – about £10 million in today’s money.

The expedition was led by Captain George Nares and the scientific work was conducted by Wyville Thomson assisted by Sir John Murray, John Young Buchanan, Henry Nottidge Moseley, and the German naturalist Rudolf von Willemoes-Suhm.

They were also interested in supporting the theories of Charles Darwin and disproving the azoic theory of a dead zone below 1,800 feet.

In December 1874, Nares left the Challenger at Hong Kong to assume command of the British Arctic Expedition of 1875-1876, and Captain Frank Tourle Thomson took his place.

The biological findings received a great interest. All the new species were carefully described, and were sketched by the expedition’s artist, J.J. Wild, but the most famous paintings are those from Hoyle’s monographic studies on cephalopods and the Haeckel’s serie included in “Kunstformen der Natur”.

When in 1895, the first reports of the Challenger were published John Murray summed up the significance of the voyage by calling it “the greatest advance in the knowledge of our planet since the celebrated discoveries of the fifteenth and sixteenth centuries“.

Among the Challenger Expedition’s discoveries is included the first ever rough map of the ocean floor and the finding of an enormous depression in the north-west Pacific Ocean representing the deepest places in the Earth’s crust, now called the Mariana trenches, the deepest point in it is named the Challenger Deep in honor of the expedition. But the greatest discovery of the expedition would be that of the Mid-Atlantic ridge, a mountain chain extending the entire length of the Atlantic Ocean near its center.

When the voyage came to an end in 1876, only 144 crew remained on the ship from the original 216 members. Seven people had died, 26 were left in hospitals or were unable to continue the journey, and several had deserted at the various ports of call. After the dead of Thomson in 1882, John Murray became director and edited the Expedition Reports.

The biggest legacy of the Challenger expedition was the establishment of the science of oceanography, based in international and interdisciplinary scientific cooperation.

References:

Deacon, M., Rice, T. and Summerhayes, C. (eds.) (2001) Understanding the oceans: a century of ocean exploration, London, UK, UCL Press.