Principal Rivers of the World The following table lists the principal rivers of the world including the name, source location, outflow, and approximate length. The Nile is the world's longest river stretching 6,690 kilometers. (See Rivers of the United Statesfor other U.S. rivers.) Approx. length RiverSourceOutflowmi.km NileTributaries of Lake Victoria, AfricaMediterranean Sea4,1806,690 AmazonGlacier-fed lakes, PeruAtlantic Ocean3,9126,296 Mississippi-Missouri- Red Rock Source of Red Rock, MontanaGulf of Mexico3,7105,970 Chang Jiang (Yangtze)Tibetan plateau, ChinaChina Sea3,6025,797 ObAltai Mts., RussiaGulf of Ob3,4595,567 Huang He(Yellow)Eastern part of Kunlan Mts., West ChinaGulf of Chihli2,9004,667 YeniseiTannu-Ola Mts., western Tuva, RussiaArctic Ocean2,8004,506 ParanáConfluence of Paranaiba and Grande riversRío de la Plata2,7954,498 IrtishAltai Mts., RussiaOb River2,7584,438 Zaire (Congo)Confluence of Lualab and Luapula rivers, CongoAtlantic Ocean2,7164,371 Heilong (Amur)Confluence of Shilka (Russia) and Argun (Manchuria) riversTatar Strait2,7044,352 LenaBaikal Mts., RussiaArctic Ocean2,6524,268 MackenzieHead of Finlay River, British Columbia, CanadaBeaufort Sea (Arctic Ocean)2,6354,241 NigerGuineaGulf of Guinea2,6004,184 MekongTibetan highlandsSouth China Sea2,5004,023 MississippiLake Itasca, MinnesotaGulf of Mexico2,3483,779 MissouriConfluence of Jefferson, Gallatin, and Madison rivers, MontanaMississippi River2,3153,726 VolgaValdai plateau, RussiaCaspian Sea2,2913,687 MadeiraConfluence of Beni and Maumoré rivers, Bolivia–Brazil boundaryAmazon River2,0123,238 PurusPeruvian AndesAmazon River1,9933,207 São FranciscoSouthwest Minas Gerais, BrazilAtlantic Ocean1,9873,198 YukonJunction of Lewes and Pelly rivers, Yukon Territory, CanadaBering Sea1,9793,185 St. LawrenceLake OntarioGulf of St. Lawrence1,9003,058 Rio GrandeSan Juan Mts., ColoradoGulf of Mexico1,8853,034 BrahmaputraHimalayasGanges River1,8002,897 IndusHimalayasArabian Sea1,8002,897 DanubeBlack Forest, GermanyBlack Sea1,7662,842 EuphratesConfluence of Murat Nehri and Kara Su rivers, TurkeyShatt-al-Arab1,7392,799 DarlingCentral part of Eastern Highlands, AustraliaMurray River1,7022,739 Zambezi11°21'S, 24°22'E, ZambiaMozambique Channel1,7002,736 TocantinsGoiás, BrazilPará River1,6772,699 MurrayAustralian Alps, New South WalesIndian Ocean1,6092,589 NelsonHead of Bow River, western Alberta, CanadaHudson Bay1,6002,575 ParaguayMato Grosso, BrazilParaná River1,5842,549 UralSouthern Ural Mts., RussiaCaspian Sea1,5742,533 GangesHimalayasBay of Bengal1,5572,506 Amu Darya (Oxus)Nicholas Range, Pamir Mts., TurkmenistanAral Sea1,5002,414 JapuráAndes, ColombiaAmazon River1,5002,414 SalweenTibet, south of Kunlun Mts.Gulf of Martaban1,5002,414 ArkansasCentral ColoradoMississippi River1,4592,348 ColoradoGrand County, ColoradoGulf of California1,4502,333 DnieperValdai Hills, RussiaBlack Sea1,4192,284 Ohio- AlleghenyPotter County, PennsylvaniaMississippi River1,3062,102 IrrawaddyConfluence of Nmai and Mali rivers, northeast BurmaBay of Bengal1,3002,092 OrangeLesothoAtlantic Ocean1,3002,092 OrinocoSerra Parima Mts., VenezuelaAtlantic Ocean1,2812,062 PilcomayoAndes Mts., BoliviaParaguay River1,2421,999 Xi Jiang (Si Kiang)Eastern Yunnan Province, ChinaChina Sea1,2361,989 ColumbiaColumbia Lake, British Columbia, CanadaPacific Ocean1,2321,983 DonTula, RussiaSea of Azov1,2231,968 SungariChina–North Korea boundaryAmur River1,2151,955 SaskatchewanCanadian Rocky Mts.Lake Winnipeg1,2051,939 PeaceStikine Mts., British Columbia, CanadaGreat Slave River1,1951,923 TigrisTaurus Mts., TurkeyShatt-al-Arab1,1801,899

Oceans and Seas The following table lists the world's oceans and seas, according to area and average depth, including the Pacific Ocean, Atlantic Ocean, Indian Ocean, Southern Ocean, Mediterranean Sea, Arctic Ocean, Caribbean Sea, Bering Sea, and more. NameAreaAverage depthGreatest known depthPlace of greatest known depth sq. mi.sq. kmft.mft.m Pacific Ocean60,060,700155,557,00013,2154,02836,19811,033Mariana Trench Atlantic Ocean29,637,90076,762,00012,8803,92630,2469,219Puerto Rico Trench Indian Ocean26,469,50068,556,00013,0023,96324,4607,455Sunda Trench Southern Ocean17,848,30020,327,00013,100–16,4004,000–5,00023,7367,235South Sandwich Trench Arctic Ocean5,427,00014,056,0003,9531,20518,4565,62577°45'N; 175°W Mediterranean Sea21,144,8002,965,8004,6881,42915,1974,632Off Cape Matapan, Greece Caribbean Sea1,049,5002,718,2008,6852,64722,7886,946Off Cayman Islands South China Sea895,4002,319,0005,4191,65216,4565,016West of Luzon Bering Sea884,9002,291,9005,0751,54715,6594,773Off Buldir Island Gulf of Mexico615,0001,592,8004,8741,48612,4253,787Sigsbee Deep Okhotsk Sea613,8001,589,7002,74983812,0013,658146°10'E; 46°50'N East China Sea482,3001,249,2006171889,1262,78225°16'N; 125°E Hudson Bay475,8001,232,300420128600183Near entrance Japan Sea389,1001,007,8004,4291,35012,2763,742Central Basin Andaman Sea308,000797,7002,85487012,3923,777Off Car Nicobar Island North Sea222,100575,200308942,165660Skagerrak Red Sea169,100438,0001,6114917,2542,211Off Port Sudan Baltic Sea163,000422,200180551,380421Off Gotland NOTE: For Caspian Sea,see Large Lakes of the World. 1. A decision by the International Hydrographic Organization in spring 2000 delimited a fifth world ocean. 2. Includes Black Sea and Sea of Azov.

Mortals on Mount Olympus: A History of Climbing Everest Called Chomolungma (“goddess mother of the world”) in Tibet and Sagarmatha (“goddess of the sky”) in Nepal, Mount Everest once went by the pedestrian name of Peak XV among Westerners. That was before surveyors established that it was the highest mountain on Earth, a fact that came as something of a surprise—Peak XV had seemed lost in the crowd of other formidable Himalayan peaks, many of which gave the illusion of greater height. In 1852 the Great Trigonometrical Survey of India measured Everest's elevation as 29,002 feet above sea level. This remarkably accurate figure remained the officially accepted height for more than one hundred years. In 1955 it was adjusted by a mere 26 feet to 29,028 (8,848 m). The mountain received its official name in 1865 in honor of Sir George Everest, the British Surveyor General from 1830–1843 who had mapped the Indian subcontinent. He had some reservations about having his name bestowed on the peak, arguing that the mountain should retain its local appellation, the standard policy of geographical societies. Pretenders to the Throne Before the Survey of India, a number of other mountains ranked supreme in the eyes of the world. In the seventeenth and eighteenth centuries, the Andean peak Chimboraso was considered the highest. At a relatively unremarkable 20,561 feet (6,267 m), it is in fact nowhere near the highest, surpassed by about thirty other Andean peaks and several dozen in the Himalayas. In 1809, the Himalayan peak Dhaulagiri (26,810 ft.; 8,172 m) was declared the ultimate, only to be shunted aside in 1840 by Kanchenjunga (28,208 ft.; 8,598 m), which today ranks third. Everest's status has been unrivaled for the last century-and-a-half, but not without a few threats. The most recent challenge came from a 1986 American expedition climbing K2 (28,250 ft., 8,611 m) in the Karakoram range. According to their measurements, K2 was actually 29,284 feet, beating Everest by a cool 256 feet. Had this figure been accepted, mountaineering history would have required drastic revision: Everest would have taken a back seat to K2, no longer thene plus ultraof geographical extremes. The Third Pole Once the North and South Poles had been reached by explorers, the next geographical feat to capture the international imagination was Everest, often called the Third Pole. Attempts to climb Everest began in the 1921, when the forbidden kingdom of Tibet opened its borders to outsiders. On June 8, 1924, two members of a British expedition, George Mallory and Andrew Irvine, attempted the summit. Famous for his retort to the press—“because it's there”—when asked why he wanted to climb Everest, Mallory had already failed twice at reaching the summit. The two men were last spotted “going strong” for the top until the clouds perpetually swirling around Everest engulfed them. They vanished for good. Mallory's body was not found for another 75 years, and it did not clear up the mystery as to whether the two men made it to the top before the mountain killed them. Ten more expeditions over a period of thirty years failed to conquer Everest, with 13 losing their lives. Then, on May 29, 1953, Edmund Hillary, a New Zealand beekeeper, and Tenzing Norgay, an acclaimed Sherpa climber, became the first to reach the roof of the world. Their climb was made from the Nepalese side, which had eased its restrictions on foreigners at about the same time that Tibet, invaded in 1950 by China, shut its borders. World famous overnight, Hillary became a hero of the British empire—the news reached London just in time for Elizabeth II's coronation—and Norgay was touted as a symbol of national pride by three separate nations: Nepal, Tibet, and India. Into the Death Zone Although not considered one of the most technically challenging mountains to climb (K2 is more difficult), the dangers of Everest include avalanches, crevasses, ferocious winds up to 125 mph, sudden storms, temperatures of 40°F below zero, and oxygen deprivation. In the “death zone”—above 25,000 feet—the air holds only a third as much oxygen as at sea level, heightening the chances of hypothermia, frostbite, high-altitude pulmonary edema (when the lungs fatally fill with fluid) and high-altitude cerebral edema (when the oxygen-starved brain swells up). Even when breathing bottled oxygen, climbers experience extreme fatigue, impaired judgment and coordination, headaches, nausea, double vision, and sometimes hallucinations. Expeditions spend weeks, sometimes months, acclimatizing, and usually attempt Everest only in May and October, avoiding the winter snows and the summer monsoons. After Hillary and Norgay's ascent of Everest, other records were broken, including the first ascent by a woman, the first solo ascent, the first to traverse up one route and down another, and the first descent on skis.

Everest Is Higher Than Ever As of Nov. 11, 1999, the new official height of Mount Everest was announced as 29,035 feet, or 8,850 meters—6 feet, or 2 meters, higher than the previously accepted measurement. The new elevation was determined using satellite-based technology: the Trimble Global Positioning System (GPS). A team of seven climbers measured the mountain from the summit on May 5, 1999, collecting data from various GPS satellite receivers at the very top of Everest. It took the climbers a number of attempts over several years until they were able to successfully set up the equipment at the summit. Everest was first measured in 1852 in the Great Trigonometrical Survey of India, which established the peak as the highest on Earth. That figure (29,002 feet above sea level) remained Everest’s officially accepted height for more than one hundred years. The original 1852 measurement was remarkably accurate: in 1955 the elevation was adjusted by a mere 26 feet to 29,028 feet (8,848 meters).

New Island Emerges off the Coast of Germany Norderoogsand, a new island in the North Sea, is already a home to many birds and plants. By Jennie Wood A new island has appeared in the North Sea. A new island has emerged from the North Sea, off the coast of Germany, located sixteen miles from the German state, Schleswig Holstein. The 34 acre island has been named Norderoogsand, but it is being referred to as Bird Island because many birds, including sea gulls, grey geese, ducks, and peregrine falcons have been found there nesting or feeding. Forty-nine plant species have also been found on the island. The island appeared slowly over a ten year period from 2003 through 2013. The land mass emerged due to tidal action, not global warming. The island’s appearance surprised scientists because that area of the North Sea has strong winds and shifting tides. However, Norderoogsand was helped by its position between other islands. The surrounding islands helped to shelter it. Also, there have been very few storm surges in the area over the last decade. In early 2013, Martin Stock, a National Park Management biologist, said in a statement, “A strong storm flood could wipe the island out overnight. The plants do not have the roots necessary yet to bind the dunes together.” Other scientists have also warned that a major storm could destroy Norderoogsand, but, for now, birds and plants have a new home.