The turning point of modern oceanography occurred between 1872 and 1876 when the HMS Challenger set sail for the sole purpose of exploring the world’s oceans. The Challenger Expedition sought to collect data on ocean temperatures, water chemistry, currents, marine life, and the seafloor. The scientists involved were also interesting in supporting the theories of Charles Darwin and disproving the azoic theory of a dead zone below 1,800 feet. The small warship, a British Navy corvette, was converted into the first oceanographic ship complete with laboratories and scientific equipment. British naturalist John Murray and Scottish naturalist Charles Wyville Thomson led the expedition, shaping the science of oceanography forever, essentially creating the field. Thomson previously dredged in the North Atlantic and Mediterranean, discovering some interesting sea creatures and then convinced the British government to fund the project.
Challenger’s crew consisted of 243 people, six of whom were scientists. The ship departed Portsmouth, England in December of 1872, traveling first to the South Atlantic, around the Cape of Good Hope in South Africa. The expedition crossed the Indian Ocean and into the Antarctic Circle, then went to Australia and New Zealand. Following this, she went to the Hawaiian Islands and south to Cape Horn at the bottom of South America, finally returning to England in May of 1876 and having covered a distance of around 69,000 miles, exploring all oceans except the Arctic.
The Challenger Expedition collected data at 360 stations, measuring temperature and depth, as well as taking water samples and dredging. Using a hydrometer on board, they measured salinity and density. Though the main focus of the mission was to study the oceans, they also encountered several unexplored islands and collected plant and animal samples that were returned to England. Over the course of the expedition 4,700 new species of animals were discovered as well as the Marianas Trench in the Pacific, which is one of the deepest parts of the ocean averaging depths of 26,850 feet. The area where the Challenger Expedition took the ocean depth sounding is very near the deepest depth of 37,800 feet and is now known as the Challenger Deep. In the Atlantic, the rise called the Mid-Atlantic Ridge was found. The scientists compiled the first plots of currents and ocean temperatures.
The work of the Challenger Expedition was groundbreaking simply by being the first government funded, scientific exploration of the the ocean on such a large scale. The discoveries made also encouraged other countries to take up studies of the ocean afterward. Prior to the Challenger, very little was known about the seas despite all of the sailing that had been occurring for centuries. Most scientists believed much of the ocean was lifeless, but the Challenger Expedition proved otherwise. Though technology has improved, today’s oceanographers still collect the same types of data and continue to make new discoveries in much the same fashion.