The Challenger expedition of 1872–1876 was a scientific programme that made many discoveries to lay the foundation of oceanography. The expedition was named after the naval vessel that undertook the trip, HMS Challenger.
The expedition, initiated by William Benjamin Carpenter, was placed under the scientific supervision of Sir Charles Wyville Thomson—of the University of Edinburgh and Merchiston Castle School—assisted by five other scientists, including Sir John Murray, a secretary-artist and a photographer. The Royal Society of London obtained the use of Challenger from the Royal Navy and in 1872 modified the ship for scientific tasks at Sheerness, equipping it with separate laboratories for natural history and chemistry. The expedition, led by Captain George Nares, sailed from Portsmouth, England, on 21 December 1872. Other naval officers included Commander John Maclear.
Under the scientific supervision of Thomson himself, the ship travelled approximately 68,890 nautical miles (79,280 miles; 127,580 kilometres) surveying and exploring. The result was the Report of the Scientific Results of the Exploring Voyage of H.M.S. Challenger during the years 1873–76 which, among many other discoveries, catalogued over 4,000 previously unknown species. John Murray, who supervised the publication, described the report as "the greatest advance in the knowledge of our planet since the celebrated discoveries of the fifteenth and sixteenth centuries". Challenger sailed close to Antarctica, but not within sight of it. However, it was the first scientific expedition to take pictures of icebergs.
The expedition, which circumnavigated the Earth, collected data by lowering sounding lines to the bottom of the ocean floor to measure its depth and collect sediment samples, by collecting marine organisms by means of dredges lowered to the ocean floor and trawls lowered into the water at different depths, by measuring temperature at various depths and by collecting samples of seawater at standard depths for chemical analysis. They collected plankton samples and recorded the speed and direction of ocean surface currents. Samples were preserved in brine or alcohol, or dried, then brought to Europe and distributed to various experts to analyse.
To enable it to probe the depths, 15 of Challenger's 17 guns were removed and its spars reduced to make more space available. Laboratories, extra cabins and a special dredging platform were installed. Challenger used mainly sail power during the expedition; the steam engine was used only for dragging the dredge, station-keeping while taking soundings, and entering and leaving ports. It was loaded with specimen jars, filled with alcohol for preservation of samples, microscopes and chemical apparatus, trawls and dredges, thermometers, barometers, water sampling bottles, sounding leads, devices to collect sediment from the sea bed and great lengths of rope with which to suspend the equipment into the ocean depths.
Because of the novelty of the expedition, some of the equipment was invented or specially modified for the occasion. It carried 181 miles (291 km) of Italian hemp rope for sounding.
On its landmark journey circumnavigating the globe, 492 deep sea soundings, 133 bottom dredges, 151 open water trawls and 263 serial water temperature observations were taken. About 4,700 new species of marine life were discovered.
The scientific work was conducted by Wyville Thomson, John Murray, John Young Buchanan, Henry Nottidge Moseley and Rudolf von Willemoes-Suhm. Frank Evers Bed was appointed prosector. The official expedition artist was John James Wild. As well as Nares and Maclear, others that were part of the naval crew included Pelham Aldrich, George Granville Campbell and Andrew Francis Balfour (one of the sons of Scottish botanist John Hutton Balfour). Also among the officers was Thomas Henry Tizard, who had carried out important hydrographic observations on previous voyages. Though he was not among the civilian scientific staff, Tizard would later help write the official account of the expedition, and also become a Fellow of the Royal Society.
The original ship's complement included 21 officers and around 216 crew members. By the end of the voyage, this had been reduced to 144 due to deaths, desertions, personnel being left ashore due to illness, and planned departures.
Challenger reached Hong Kong in December 1874, at which point Nares and Aldrich left the ship to take part in the British Arctic Expedition. The new captain was Frank Tourle Thomson. The second-in-command, and the most senior officer present throughout the entire expedition, was Commander John Maclear. Willemoes-Suhm died and was buried at sea on the voyage to Tahiti. Lords Campbell and Balfour left the ship in Valparaíso, Chile, after being promoted.
The first leg of the expedition took the ship from Portsmouth (December 1872) south to Lisbon (January 1873) and then on to Gibraltar. The next stops were Madeira and the Canary Islands (both February 1873). The period from February to July 1873 was spent crossing the Atlantic westwards from the Canary Islands to the Virgin Islands, then heading north to the North Atlantic archipelago and Imperial fortress colony of Bermuda (home base of the North America and West Indies Station), east to the Azores, back to Madeira, and then south to the Cape Verde Islands. During this period, there was a detour in April and May 1873, sailing from Bermuda north to Halifax and back, crossing the Gulf Stream twice with the reverse journey crossing further to the east.
After leaving the Cape Verde Islands in August 1873, the expedition initially sailed south-east and then headed west to reach St Paul's Rocks. From here, the route went south across the equator to Fernando de Noronha during September 1873, and onwards that same month to Bahia (now called Salvador) in Brazil. The period from September to October 1873 was spent crossing the Atlantic from Bahia to the Cape of Good Hope, touching at Tristan da Cunha on the way.
December 1873 to February 1874 was spent sailing on a roughly south-eastern track from the Cape of Good Hope to the parallel of 60 degrees south. The islands visited during this period were the Prince Edward Islands, the Crozet Islands, the Kerguelen Islands and Heard Island. February 1874 was spent travelling south and then generally eastwards in the vicinity of the Antarctic Circle, with sightings of icebergs, pack ice and whales. The route then took the ship north-eastward and away from the ice regions in March 1874, with the expedition reaching Melbourne in Australia later that month. The journey eastward along the coast from Melbourne to Sydney took place in April 1874, passing by Wilsons Promontory and Cape Howe.
When the voyage resumed in June 1874, the route went east from Sydney to Wellington in New Zealand, followed by a large loop north into the Pacific calling at Tonga and Fiji, and then back westward to Cape York in Australia by the end of August. The ship arrived in New Zealand in late June and left in early July. Before reaching Wellington (on New Zealand's North Island), brief stops were made at Port Hardy (on d'Urville Island) and Queen Charlotte Sound and Challenger passed through the Cook Strait to reach Wellington.
The route from Wellington to Tonga went along the east coast of New Zealand's North Island, and then north and east into the open Pacific, passing by the Kermadec Islands en route to Tongatabu, the main island of the Tonga archipelago (then known as the Friendly Islands). The waters around the Fijian islands, a short distance to the north-west of Tonga, were surveyed during late July and early August 1874. The ship's course was then set westward, reaching Raine Island—on the outer edge of the Great Barrier Reef—at the end of August and thence arriving at Cape York, at the tip of Australia's Cape York Peninsula.
Over the following three months, from September to November 1874, the expedition visited several islands and island groups while sailing from Cape York to China and Hong Kong (then a British colony). The first part of the route passed north and west over the Arafura Sea, with New Guinea to the north-east and the Australian mainland to the south-west. The first islands visited were the Aru Islands, followed by the nearby Kai Islands. The ship then crossed the Banda Sea touching at the Banda Islands, to reach Amboina (Ambon Island) in October 1874, and then continuing to Ternate Island. At the time, all these islands were part of Netherlands East-Indies and are since 1949 part of Indonesia.