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Tybee Island, Georgia
Tybee Island, Georgia: the northernmost of Georgia's barrier islands at the mouth of the Savannah River, near Savannah. Known for its 1736 lighthouse, the 1862 rifled-cannon bombardment of Fort Pulaski, Fort Screven, a $182 million visitor economy, and recurring Corps beach nourishment.
Ubekendt Ejland
Ubekendt Ejland (Illorsuit, Igdlorssuit) is a volcanic island in the Uummannaq region of central West Greenland, built of Vaigat Formation picrites and hosting the Sarqâta qáqâ gabbro-granophyre complex.
Ubinas
Ubinas, Peru's most active andesitic stratovolcano in Moquegua region, 70 km from Arequipa; frequent VEI 2-3 eruptions from a 1.4-km-wide summit crater, most recently 2023-2024.
Ucayali - Urubamba Piedmont
Ucayali-Urubamba Piedmont, FEOW freshwater ecoregion 317 in Peru, a 250-750 m Andes-Amazon transition of whitewater rivers; nearly 21 endemic fish species, threatened by dams and Camisea gas development.
Udayagiri and Khandagiri Caves
The Udayagiri and Khandagiri Caves (ଉଦୟଗିରି ଓ ଖଣ୍ଡଗିରି ଗୁମ୍ଫା) are 33 rock-cut caves near Bhubaneswar, India, carved as Jain monk retreats in the 2nd century BCE under King Kharavela.
Udaygiri Mound
Udaygiri Mound, also written Udayagiri, is a sandstone hill near Vidisha, Madhya Pradesh, India, bearing twenty rock-cut caves carved under Gupta patronage in the late 4th and early 5th centuries.
Uinta Mountains
Uinta Mountains: east-west trending range in northeastern Utah and northwest Colorado, 150 miles long, Utah's highest with Kings Peak 13,528 ft; Laramide uplift 70-34 Ma on Precambrian Cheyenne Belt structure.
Ulawun
Ulawun, the Father, is a 2,334 m basaltic-to-andesitic stratovolcano on New Britain, Papua New Guinea, the highest volcano of the Bismarck arc, a Decade Volcano erupting since at least 1700, with a VEI 4 eruption in 2019 and a deadly November 2023 eruption.
Uludoruk
Uludoruk, also called Reşko or Gelyaşin, is a 4,135 m peak in the Cilo Mountains, Hakkâri Province, Turkey's second-highest mountain after Ağrı, and carries Turkey's largest valley glacier.
Ulugh Muztagh
Ulugh Muztagh, the 'Great Ice Mountain' in Turki, is a 6,973 m massif in the Arkatag Shan, central Kunlun Mountains, China. Once reputed 7,723 m and a volcano, it was first climbed and remeasured at about 6,987 m by the 1985 joint Chinese-American expedition.
Uluru
Uluru, also known as Ayers Rock, is a 348-meter sandstone inselberg in Uluṟu-Kata Tjuṯa National Park in central Australia. Sacred to the Aṉangu, it was returned to them in 1985 and its climb closed in 2019.
Uluru Rock Art
Uluru Rock Art consists of paintings in caves and rock shelters around the base of Uluru in central Australia, made by the Aṉangu people to teach Tjukurpa, their traditional law.
Umboi Island
Umboi Island, a 930 km2 volcanic island in Vitiaz Strait, Morobe Province, Papua New Guinea, largest of PNG's north coastal volcanic islands; 13 x 17 km caldera, no historical eruptions, rich endemic biodiversity and Kovai population.
Umnak Island
Umnak Island is a dumbbell-shaped volcanic island in the eastern Aleutian Islands of Alaska, separated from Unalaska by Umnak Pass and holding the chain's earliest known settlement.
Uncompahgre Peak
Uncompahgre Peak, highest summit of Colorado's San Juan Mountains at 14,318 ft (LiDAR; 14,309 ft in 1963 USGS survey), sixth-highest Colorado fourteener, in Uncompahgre Wilderness near Lake City; Class 2 South Ridge route.
Undara Volcanic National Park
Undara Volcanic National Park, Queensland, protects Australia's longest lava tube system, formed by an eruption about 190,000 years ago that flowed over 160 km; over 70 caves, Bayliss Cave biodiversity, Ewamian country.
Underground lake
Underground lake, also called cave lake or karst lake: standing water pooled in caves, mostly in karst terrain. Key facts include sump entrances, speleogenetic role, Škocjan Dead Lake, Devils Hole, and Yucatán flooded systems.
Unga Island
Unga Island (Ugnaasaqax, formerly Ounga Island) is the largest and westernmost Shumagin Island off the Alaska Peninsula, Alaska; 170.73 sq mi, 36th largest US island, with a Tertiary petrified sequoia forest, historic Apollo gold mines, and the abandoned village of Unga.
Ungava Peninsula
Ungava Peninsula (Péninsule d'Ungava), northwestern arm of the Labrador Peninsula in northern Quebec, bounded by Hudson Bay, Hudson Strait, Ungava Bay, and the rivière aux Feuilles; 252,000 km² tundra plateau, Quebec's largest natural province, with continuous permafrost and coastal Inuit villages in Nunavik.
University Ice Cap
University Ice Cap (UN) is an ice cap on October Revolution Island, Severnaya Zemlya, Russian Arctic, adjacent to Karpinsky Ice Cap; first cored in 2021, showing thick melt layers and no surging.
Unmanaged land
Unmanaged land is land without direct human interventions for production, ecological, or social functions, the IPCC complement of managed land; its GHG fluxes go unreported, covering about 8% of US land and 34% of Canadian forests.
Unnamed point
Unnamed point: a summit with no official name, labeled in peak lists by elevation (Peak 2390, p. 6436) and grid coordinates; common in Andes catalogs, counted as independent peaks by prominence thresholds.
Upernivik Ø
Upernivik Ø (Upernivik Island) is an uninhabited, heavily glaciated island in the Umanak district of northwest Greenland at 71°16'N, 52°45'W, rising above 2,100 m, about one third ice-covered, separated from Ubekendt Ejland by Igdlorssuit Sund.
Upland
Upland: an extensive interior region of high land with low to moderate surface relief (GeoNames UPLD); in Britain, high ground typically above 300-400 m of moorland, heath, bog and rough grassland, grazed by hill farmers and rich in peat, carbon and drinking water.
Upper Indus
The Upper Indus, also called the Upper Indus Basin (UIB), is the mountainous headwater of the Indus River above Tarbela Dam, spanning the Hindu Kush, Karakoram, and Himalaya.
Upper Peninsula of Michigan
Michigan's Upper Peninsula (U.P.), the northern peninsula bordered by Lake Superior, Wisconsin, and Lakes Michigan and Huron; home of Yooper identity, Keweenaw copper and iron mining history, 917 miles of Lake Superior shoreline, and Michigan's entire wolf population.
Ural Mountains (Уральские горы)
The Ural Mountains (Уральские горы) are a 2,500 km Russian range forming the conventional Europe-Asia boundary, formed 250-300 million years ago, with Mount Narodnaya (1,895 m) as highest point and over 1,000 mineral types.
Uru Island
Uru Island, also written Ururu Island, is a small island off the eastern coast of Malaita Island, near Kwalakwala and Ato'ifi in Malaita Province, Solomon Islands.
Urup
Urup (Uruppu, 得撫島) is the fourth largest island of the Greater Kuril Ridge in the southern Kuril chain, Sea of Okhotsk; volcanic, 1,450 sq km, Russian since 1945, formerly Russo-Japanese border island.
Utøya
Utøya is an island in Tyrifjorden, Hole municipality, Norway, owned by the Workers' Youth League (AUF) and site of its summer camp; on 22 July 2011 a right-wing terrorist killed 69 people there. Rebuilt as a memorial and learning site.