note 1: world's smallest continent but sixth-largest country; the largest country in Oceania, the largest country entirely in the Southern Hemisphere, and the largest country without land borders; the only continent without glaciers; the invigorating sea breeze known as the "Fremantle Doctor" affects the city of Perth on the west coast and is one of the most consistent winds in the world

note 2: the Great Dividing Range that runs along eastern Australia is that continent’s longest mountain range and the third-longest land-based range in the world; the term "Great Dividing Range" refers to the fact that the mountains form a watershed crest from which all of the rivers of eastern Australia flow – east, west, north, and south

note 1: landlocked; strategic location at the crossroads of central Europe with many easily traversable Alpine passes and valleys; major river is the Danube; population is concentrated on eastern lowlands because of steep slopes, poor soils, and low temperatures elsewhere

note 2: the world's largest and longest ice cave system at 42 km (26 mi) is the Eisriesenwelt (Ice Giants World) inside the Hochkogel mountain near Werfen, about 40 km south of Salzburg; ice caves are bedrock caves that contain year-round ice formations; they differ from glacial caves, which are transient and are formed by melting ice and flowing water within and under glaciers

note 1: landlocked; shares control of Lago Titicaca, world's highest navigable lake (elevation 3,805 m), with Peru

note 2: the southern regions of Peru and the extreme northwestern part of Bolivia are considered to be the place of origin for the common potato

note 1: archipelago of 55 islands; Diego Garcia, the largest and southernmost island, occupies a strategic location in the central Indian Ocean; the island is the site of a joint US-UK military facility

note 2: Diego Garcia is the only inhabited island of the BIOT and one of only two British territories where traffic drives on the right, the other being Gibraltar

note 1: second-largest country in world (after Russia) and largest in the Americas; strategic location between Russia and US via north polar route; approximately 90% of the population is concentrated within 160 km (100 mi) of the US border

note 2: Canada has more fresh water than any other country and almost 9% of Canadian territory is water; Canada has at least 2 million and possibly over 3 million lakes - that is more than all other countries combined

note 1: Chad is the largest of Africa's 16 landlocked countries

note 2: not long ago - geologically speaking - what is today the Sahara was green savannah teeming with wildlife; during the African Humid Period, roughly 11,000 to 5,000 years ago, a vibrant animal community, including elephants, giraffes, hippos, and antelope lived there; the last remnant of the "Green Sahara" exists in the Lakes of Ounianga (oo-nee-ahn-ga) in northern Chad, a series of 18 interconnected freshwater, saline, and hypersaline lakes now protected as a World Heritage site

note 3: Lake Chad, the most significant water body in the Sahel, is a remnant of a former inland sea, paleolake Mega-Chad; at its greatest extent, sometime before 5000 B.C., Lake Mega-Chad was the largest of four Saharan paleolakes that existed during the African Humid Period; it covered an area of about 400,000 sq km (150,000 sq mi), roughly the size of today's Caspian Sea

note 1: the longest north-south trending country in the world, extending across 39 degrees of latitude; strategic location relative to sea lanes between the Atlantic and Pacific Oceans (Strait of Magellan, Beagle Channel, Drake Passage)

note 2: Chile is one of the countries along the Ring of Fire, a belt of active volcanoes and earthquake epicenters bordering the Pacific Ocean; up to 90% of the world's earthquakes and some 75% of the world's volcanoes occur within the Ring of Fire

note 3: the Atacama Desert - the driest desert in the world - spreads across the northern part of the country; Ojos del Salado (6,893 m) in the Atacama Desert is the highest active volcano in the world, Chile's tallest mountain, and the second highest in the Western Hemisphere and the Southern Hemisphere - its small crater lake (at 6,390 m) is the world's highest lake

note 1: world's fourth largest country (after Russia, Canada, and US) and largest country situated entirely in Asia; Mount Everest on the border with Nepal is the world's tallest peak above sea level

note 2: the largest cave chamber in the world is the Miao Room, in the Gebihe cave system at China's Ziyun Getu He Chuandong National Park, which encloses some 10.78 million cu m (380.7 million cu ft) of volume

note 3: China appears to have been the center of domestication for two of the world's leading cereal crops: millet in the north along the Yellow River and rice in the south along the lower or middle Yangtze River

note 1: second largest country in Africa (after Algeria) and largest country in Sub-Saharan Africa; straddles the equator; dense tropical rain forest in central river basin and eastern highlands; the narrow strip of land that controls the lower Congo River is the DRC's only outlet to the South Atlantic Ocean

note 2: because of its speed, cataracts, rapids, and turbulence the Congo River, most of which flows through the DRC, has never been accurately measured along much of its length; nonetheless, it is conceded to be the deepest river in the world; estimates of its greatest depth vary between 220 and 250 meters

note 1: landlocked; strategically located astride some of oldest and most significant land routes in Europe; Moravian Gate is a traditional military corridor between the North European Plain and the Danube in central Europe

note 2: the Hranice Abyss in Czechia is the world's deepest surveyed underwater cave at 404 m (1,325 ft); its survey is not complete and it could end up being some 800-1,200 m deep

note 1: landlocked - entire coastline along the Red Sea was lost with the de jure independence of Eritrea on 24 May 1993; Ethiopia is, therefore, the most populous landlocked country in the world; the Blue Nile, the chief headstream of the Nile by water volume, rises in T'ana Hayk (Lake Tana) in northwest Ethiopia

note 2: three major crops are believed to have originated in Ethiopia: coffee, grain sorghum, and castor bean

note 1: strategically located east of the Black Sea; Georgia controls much of the Caucasus Mountains and the routes through them

note 2: the world's four deepest caves are all in Georgia, including two that are the only known caves on earth deeper than 2,000 m: Krubera Cave at -2,197 m (-7,208 ft; reached in 2012) and Veryovkina Cave at -2,212 (-7,257 ft; reached in 2018)

note 1: strategic location on Strait of Gibraltar that links the North Atlantic Ocean and Mediterranean Sea

note 2: one of only two British territories where traffic drives on the right, the other being the island of Diego Garcia in the British Indian Ocean Territory

note 1: despite having both eastern and western coastlines (Caribbean Sea and Pacific Ocean respectively), there are no natural harbors on the west coast

note 2: Guatemala is one of the countries along the Ring of Fire, a belt of active volcanoes and earthquake epicenters bordering the Pacific Ocean; up to 90% of the world's earthquakes and some 75% of the world's volcanoes occur within the Ring of Fire

note 1: according to Indonesia's National Coordinating Agency for Survey and Mapping, the total number of islands in the archipelago is 13,466, of which 922 are permanently inhabited (Indonesia is the world's largest country comprised solely of islands); the country straddles the equator and occupies a strategic location astride or along major sea lanes from the Indian Ocean to the Pacific Ocean

note 2: Indonesia is one of the countries along the Ring of Fire, a belt of active volcanoes and earthquake epicenters bordering the Pacific Ocean; up to 90% of the world's earthquakes and some 75% of the world's volcanoes occur within the Ring of Fire

note 3: despite having the fourth largest population in the world, Indonesia is the most heavily forested region on earth after the Amazon

note 1: Lake Tiberias (Sea of Galilee) is an important freshwater source; the Dead Sea is the second saltiest body of water in the world (after Lake Assal in Djibouti)

note 2: the Malham Cave in Mount Sodom is the world's longest salt cave at 10 km (6 mi); its survey is not complete and its length will undoubtedly increase; Mount Sodom is actually a hill some 220 m (722 ft) high that is 80% salt (multiple salt layers covered by a veneer of rock)

note 3: in March 2019, there were 380 Israeli settlements,to include 213 settlements and 132 outposts in the West Bank, and 35 settlements in East Jerusalem; there are no Israeli settlements in the Gaza Strip, as all were evacuated in 2005 (2019)

note 1: strategic location in northeast Asia; composed of four main islands - from north: Hokkaido, Honshu (the largest and most populous), Shikoku, and Kyushu (the "Home Islands") - and 6,848 smaller islands and islets

note 2: Japan annually records the most earthquakes in the world; it is one of the countries along the Ring of Fire, a belt of active volcanoes and earthquake epicenters bordering the Pacific Ocean; up to 90% of the world's earthquakes and some 75% of the world's volcanoes occur within the Ring of Fire

note 1: strategic location on southern border of the US; Mexico is one of the countries along the Ring of Fire, a belt of active volcanoes and earthquake epicenters bordering the Pacific Ocean; up to 90% of the world's earthquakes and some 75% of the world's volcanoes occur within the Ring of Fire

note 2: the "Three Sisters" companion plants - winter squash, maize (corn), and climbing beans - served as the main agricultural crops for various North American Indian groups; all three apparently originated in Mexico but then were widely disseminated through much of North America; vanilla, the world's most popular aroma and flavor spice, also emanates from Mexico

note 3: the Sac Actun cave system at 348 km (216 mi) is the longest underwater cave in the world and the second longest cave worldwide, after Mammoth Cave in the United States (see "Geography - note" under United States)

note 4: the prominent Yucatan Peninsula that divides the Gulf of Mexico from the Caribbean Sea is shared by Mexico, Guatemala, and Belize; just on the northern coast of Yucatan, near the town of Chicxulub (pronounce cheek-sha-loob), lie the remnants of a massive crater (some 150 km in diameter and extending well out into the Gulf of Mexico); formed by an asteroid or comet when it struck the earth 66 million years ago, the impact is now widely accepted as initiating a worldwide climate disruption that caused a mass extinction of 75% of all the earth's plant and animal species - including the non-avian dinosaurs

note 1: consists of two main islands and a number of smaller islands; South Island, the larger main island, is the 12th largest island in the world and is divided along its length by the Southern Alps; North Island is the 14th largest island in the world and is not as mountainous, but it is marked by volcanism

note 2: New Zealand lies along the Ring of Fire, a belt of active volcanoes and earthquake epicenters bordering the Pacific Ocean; up to 90% of the world's earthquakes and some 75% of the world's volcanoes occur within the Ring of Fire

note 3: almost 90% of the population lives in cities and over three-quarters on North Island; Wellington is the southernmost national capital in the world

note 1: shares island of New Guinea with Indonesia; generally east-west trending highlands break up New Guinea into diverse ecoregions; one of world's largest swamps along southwest coast

note 2: Papua New Guinea is one of the countries along the Ring of Fire, a belt of active volcanoes and earthquake epicenters bordering the Pacific Ocean; up to 90% of the world's earthquakes and some 75% of the world's volcanoes occur within the Ring of Fire

note 1: shares control of Lago Titicaca, world's highest navigable lake, with Bolivia; a remote slope of Nevado Mismi, a 5,316 m peak, is the ultimate source of the Amazon River

note 2: Peru is one of the countries along the Ring of Fire, a belt of active volcanoes and earthquake epicenters bordering the Pacific Ocean; up to 90% of the world's earthquakes and some 75% of the world's volcanoes occur within the Ring of Fire

note 3: on 19 February 1600, Mount Huaynaputina in the southern Peruvian Andes erupted in the largest volcanic explosion in South America in historical times; intermittent eruptions lasted until 5 March 1600 and pumped an estimated 16 to 32 million metric tons of particulates into the atmosphere reducing the amount of sunlight reaching the earth's surface and affecting weather worldwide; over the next two and a half years, millions died around the globe in famines from bitterly cold winters, cool summers, and the loss of crops and animals

note 4: the southern regions of Peru and the extreme northwestern part of Bolivia are considered to be the place of origin for the common potato

note 1: for decades, the Philippine archipelago was reported as having 7,107 islands; in 2016, the national mapping authority reported that hundreds of new islands had been discovered and increased the number of islands to 7,641 - though not all of the new islands have been verified; the country is favorably located in relation to many of Southeast Asia's main water bodies: the South China Sea, Philippine Sea, Sulu Sea, Celebes Sea, and Luzon Strait

note 2: Philippines is one of the countries along the Ring of Fire, a belt of active volcanoes and earthquake epicenters bordering the Pacific Ocean; up to 90% of the world's earthquakes and some 75% of the world's volcanoes occur within the Ring of Fire

note 3: the Philippines sits astride the Pacific typhoon belt and an average of 9 typhoons make landfall on the islands each year - with about 5 of these being destructive; the country is the most exposed in the world to tropical storms

note 1: largest country in the world in terms of area but unfavorably located in relation to major sea lanes of the world; despite its size, much of the country lacks proper soils and climates (either too cold or too dry) for agriculture

note 2: Russia's far east, particularly the Kamchatka Peninsula, lies along the Ring of Fire, a belt of active volcanoes and earthquake epicenters bordering the Pacific Ocean; up to 90% of the world's earthquakes and some 75% of the world's volcanoes occur within the Ring of Fire

note 3: Mount El'brus is Europe's tallest peak; Lake Baikal, the deepest lake in the world, is estimated to hold one fifth of the world's fresh surface water

note 4: Kaliningrad oblast is an exclave annexed from Germany following World War II (it was formerly part of East Prussia); its capital city of Kaliningrad - formerly Koenigsberg - is the only Baltic port in Russia that remains ice free in the winter

note 1: world's third-largest country by size (after Russia and Canada) and by population (after China and India); Denali (Mt. McKinley) is the highest point in North America and Death Valley the lowest point on the continent

note 2: the western coast of the United States and southern coast of Alaska lie along the Ring of Fire, a belt of active volcanoes and earthquake epicenters bordering the Pacific Ocean; up to 90% of the world's earthquakes and some 75% of the world's volcanoes occur within the Ring of Fire

note 3: the Aleutian Islands are a chain of volcanic islands that divide the Bering Sea (north) from the main Pacific Ocean (south); they extend about 1,800 km westward from the Alaskan Peninsula; the archipelago consists of 14 larger islands, 55 smaller islands, and hundreds of islets; there are 41 active volcanoes on the islands, which together form a large northern section of the Ring of Fire

note 4: Mammoth Cave, in west-central Kentucky, is the world's longest known cave system with more than 650 km (405 miles) of surveyed passageways, which is nearly twice as long as the second-longest cave system, the Sac Actun underwater cave in Mexico - the world's longest underwater cave system (see "Geography - note" under Mexico);

note 5: Kazumura Cave on the island of Hawaii is the world's longest and deepest lava tube cave; it has been surveyed at 66 km (41 mi) long and 1,102 m (3,614 ft) deep

note 6: Bracken Cave outside of San Antonio, Texas is the world's largest bat cave; it is the summer home to the largest colony of bats in the world; an estimated 20 million Mexican free-tailed bats roost in the cave from March to October making it the world's largest known concentration of mammals

note 1: the country lies on major sea and air routes linking North and South America

note 2: Venezuela has some of the most unique geology in the world; tepuis are massive table-top mountains of the western Guiana Highlands that tend to be isolated and thus support unique endemic plant and animal species; their sheer cliffsides account for some of the most spectacular waterfalls in the world including Angel Falls, the world's highest (979 m) that drops off Auyan Tepui

note 1: extending 1,650 km north to south, the country is only 50 km across at its narrowest point

note 2: Son Doong in Phong Nha-Ke Bang National Park is the world's largest cave (greatest cross sectional area) and is the largest known cave passage in the world by volume; it currently measures a total of 38.5 million cu m (about 1.35 billion cu ft); it connects to Thung cave (but not yet officially); when recognized, it will add an additional 1.6 million cu m in volume; Son Doong is so massive that it contains its own jungle, underground river, and localized weather system; clouds form inside the cave and spew out from its exits and two dolines (openings (sinkhole skylights) created by collapsed ceilings that allow sunlight to stream in)