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Alazeya
Alazeya (Алазея), reka Alazeya, a 1,590 km Arctic river in northeastern Yakutia, Russia, draining the Kolyma Lowland between the Indigirka and Kolyma basins into the East Siberian Sea, with about 24,000 lakes and continuous permafrost.
Albany
Albany (Albany River), northern Ontario river, ~980 km from Lake St. Joseph to James Bay; largest Ontario watershed (137,230 km2), HBC Fort Albany fur-trade post, Albany River Provincial Park, Kashechewan ice-jam flooding.
Albemarle Sound
Albemarle Sound is a large, shallow brackish lagoon in northeastern North Carolina, the northern part of the Albemarle-Pamlico Estuarine System behind the Outer Banks barrier islands.
Albert
Albert: primarily Lake Albert (Mwitanzige, formerly Lake Mobutu Sese Seko), a transboundary rift lake shared by Uganda (54%) and DR Congo (46%), fed by the Semliki and Victoria Nile, draining as the Albert Nile; also a South Australian lake named in 1840.
Albertine Highlands
The Albertine Highlands is a freshwater ecoregion, FEOW number 541, located entirely within eastern Democratic Republic of Congo and covering the watersheds of high-lying rivers that flow toward the Lualaba River in the Congo Basin.
Alboran Sea
Alboran Sea (mar de Alborán), westernmost Mediterranean basin between Spain, Morocco, and Algeria at the Strait of Gibraltar; known for its two-layer Atlantic-Mediterranean exchange, Alboran gyres, Almeria-Oran front, and Mediterranean biodiversity hotspot status.
Aldan
Aldan (Алдан), major river in Yakutia, Russia; largest right tributary of the Lena, 2,273 km long, basin 729,000 km², mean discharge 5,110 m³/s, navigable 1,753 km, gold-bearing basin.
Aleutian Basin
Aleutian Basin: deep-water (>3,000 m) oceanic basin of the Bering Sea north of the Aleutian Islands, about the size of Texas, with 2–9 km of Cenozoic sediment over Cretaceous oceanic crust; origin debated between Eocene plate capture and backarc spreading.
Aleutian Trench
The Aleutian Trench is a deep-ocean trench in the North Pacific where the Pacific Plate subducts beneath the North American Plate along the Aleutian island arc.
Algerian Basin
Algerian Basin (Algero-Balearic Basin): deep oceanic back-arc basin of the southern western Mediterranean between Algeria, the Balearic Islands and Sardinia, opened by 16 Ma, with the Algerian Current and its large eddies.
Allegheny River
The Allegheny River (La Belle Riviere) is a 315-mile tributary forming the Ohio River at Pittsburgh with the Monongahela, draining 11,747 square miles in New York and Pennsylvania, with eight locks and dams and a 1992 Wild and Scenic designation.
Alluvium
Alluvium, or alluvial deposit, is unconsolidated clay, silt, sand, and gravel deposited by streams and rivers on beds, flood plains, deltas, and mountain bases, and it forms water-bearing alluvial aquifers.
Alpha Ridge
Alpha Ridge: large submarine volcanic high in the Amerasian Basin, Arctic Ocean, part of the Alpha-Mendeleev Ridge complex; Late Cretaceous oceanic plateau linked to HALIP magmatism, ~38 km thick crust, ages 82-90 Ma.
Alternanthera philoxeroides
Alternanthera philoxeroides, alligator weed or alligatorweed (pig weed), an amphibious Amaranthaceae herb from southern South America; invasive floating-mat aquatic weed in the USA (since 1897), China (since 1892), and Australia, spread by vegetative fragments.
Althaea officinalis
Althaea officinalis, marsh mallow, a Malvaceae perennial of Europe to Siberia and NW Africa whose dried root (Althaeae radix) is an EU-approved traditional demulcent for cough and mild gut discomfort.
Alum Bay
Alum Bay, Isle of Wight: bay at the island's western tip beside the Needles, famed for 21 shades of coloured sand, vertical Tertiary cliffs, its Elizabethan alum name, Marconi's 1897 radio station, and the Needles Landmark Attraction chairlift.
Amadeus
Lake Amadeus, Australia's Northern Territory salt lake named by Ernest Giles in 1872 after King Amadeo I of Spain; largest NT salt lake, ~180 km long, 50 km north of Uluru, a groundwater-discharge playa.
Amadjuak
Amadjuak names a large freshwater lake (about 3,115 km2) on southern Baffin Island, Nunavut, Canada, second only to Nettilling Lake, plus a former Inuit settlement, a bay, a river, and an Ordovician geologic formation.
Amazon (river, Brazil)
Amazon River (Rio Amazonas), South America's largest river: 209,000 m³/s mean discharge, ~7.05 million km² basin, ~20% of global freshwater runoff; source disputed (Apurímac/Mismi vs Mantaro); severe 2023–2024 droughts set record lows.
Amazon basin
The Amazon basin is Earth's largest drainage basin, over 7 million km² across nine South American countries, discharging about 209,000 m³/s (roughly 20% of global river flow) and formed by late Miocene river capture.
Amazon Delta
Amazon Delta: coastal region at the Amazon River mouth, Brazil; the world's largest delta by geomorphic area (84,429 km²) yet lacking a protruding delta form, with up to 1,200 Mt/y sediment discharge, macrotidal conditions over 6 m, and a subaqueous shelf clinoform.
Amazon River
The Amazon River, Rio Amazonas, is Earth's largest river by discharge, draining a roughly 7 million km2 basin across nine South American countries; its source is disputed, and drought, dams, and deforestation now stress it.
Amazonas Estuary & Coastal Drainages
Amazonas Estuary & Coastal Drainages, FEOW freshwater ecoregion 323 in Brazil, covers the Amazon estuary and coastal rivers from Itapicuru to Caciporé; 180,000 m3/s discharge, 23 endemic fishes, and the Araguari channel capture.
Amazonas Guiana Shield
Amazonas Guiana Shield (FEOW ecoregion 315): freshwater ecoregion on the southern Guiana Shield in Brazil, Guyana, and Suriname; clearwater rivers Jari, Paru, Trombetas, upper Rio Branco; about 430 fish species, nearly 40 endemic; threatened by gold mining and mercury.
Amazonas Lowlands
Amazonas Lowlands: FEOW freshwater ecoregion 316, the Amazon floodplain and lowland tributaries across Bolivia, Brazil, Colombia, Ecuador, and Peru; 206 endemic fish species, 100,000+ km² floodplain, 162,000 m³/s discharge at Óbidos.
Ambush Bay
Ambush Bay, a bay on the north coast of Joinville Island, Antarctic Peninsula, east of King Point; named by the UK in 1957, formerly Bahía Carminatti, an Adélie penguin Important Bird Area.
America Lake
America Lake refers to several lakes: Lake America (Lake Ontario renamed by 2026 executive order), American Lake in Pierce County, Washington (1,091 acres), America Lake in Brule County, South Dakota, and American Lake in Iron County, Wisconsin.
Amerigo Vespucci
Amerigo Vespucci (Americo Vespucio), Florentine merchant-navigator ca. 1451–1512, recognized South America as a new continent; his voyages of 1499 and 1501–1502 underpinned Waldseemüller's 1507 map, which named America after him.
Amgun
Amgun (Амгунь) is a 723 km left tributary of the lower Amur in Khabarovsk Krai, Russia, formed by the Suluk and Ayakit rivers, joining the Amur 146 km from its mouth; a rain-fed salmon river navigable 330 km.
Amstel
The Amstel is a Dutch river flowing into Amsterdam, partly created by a medieval canal dug between two rivers during peat reclamation. The dam in it gave Amsterdam (Amestelledamme) its name; first recorded 1275.