877 articles
Hecate Strait
Hecate Strait (Siigaay) is a 50–100 km wide seaway between Haida Gwaii and mainland British Columbia, named after HMS Hecate by Captain Richards in 1861–62; stormy, macrotidal, with glass sponge reef MPAs.
HELCOM
HELCOM (Helsinki Commission, Baltic Marine Environment Protection Commission) is the intergovernmental body governing Baltic Sea marine environmental protection under the 1974/1992 Helsinki Convention, with ten Contracting Parties, the Baltic Sea Action Plan, and six-year HOLAS assessments.
Hell Gate
Hell Gate (Dutch Hellegat) is the treacherous tidal strait of the East River between Wards Island and Astoria, Queens, New York City, where currents reach 4 knots; its rocks were blasted away at Hallett's Point in 1876 and Flood Rock on October 10, 1885. Not the Hell Gate news outlet or bridge alone.
Hellenic Trench
Hellenic Trench: deep seafloor depression system south and west of Greece marking the Hellenic subduction zone foredeep; about 2,000 km long, Mediterranean's deepest waters at 5,267 m, highest regional seismicity, and key sperm whale habitat.
Henry Hudson
Henry Hudson (c. 1565–disappeared 1611), English navigator, led four voyages (1607–1611) for the Muscovy Company, Dutch East India Company, and English backers seeking a passage to Asia; explored the Hudson River, Hudson Strait, and Hudson Bay; set adrift by mutineers in June 1611 and never seen again.
Hernando de Soto
Hernando de Soto (c. 1500–1542), Spanish conquistador of Extremadura, helped Pizarro conquer the Inca and led the 1539–1543 expedition through the American Southeast, first Europeans to reach the Mississippi River, where he died of fever.
Hero Bay
Hero Bay is a 17-mile-wide bay indenting the north side of Livingston Island, South Shetland Islands, Antarctica, between Cape Shirreff and Williams Point; named for the sloop Hero of Nathaniel B. Palmer's 1820-21 sealing fleet.
Hess Rise
Hess Rise (Mellish Rise) is a >1,000-km-long oceanic plateau in the central North Pacific, named for Harry H. Hess, formed roughly 100 Ma near the Pacific-Farallon Ridge and drilled at DSDP Sites 310, 464, 465, 466.
Hikurangi Plateau
Hikurangi Plateau: Cretaceous oceanic large igneous province east of New Zealand, fragment of the proposed Ontong Java Nui super-plateau with Ontong Java and Manihiki; rifted ~120 Ma, collided with Gondwana ~105 Ma, now subducting beneath the North Island.
Hilton Inlet
Hilton Inlet, also Hilton Bay or Ensenada Hilton, is an ice-filled inlet on the east coast of Palmer Land, Antarctica, between Cape Darlington and Cape Knowles, discovered by USAS in 1940 and named for surveyor Donald C. Hilton.
HMS Terror (1813)
HMS Terror (1813), Royal Navy bomb vessel built at Topsham, Devon; served in polar exploration with Back (1836-37), Ross's Antarctic voyage (1839-43), and Franklin's lost 1845 Northwest Passage expedition; wreck found in Terror Bay, 2016.
Hood Canal
Hood Canal: fjord-like arm of western Puget Sound, Washington, 68 miles long, named by Vancouver in 1792 for Lord Samuel Hood; known for seasonal low dissolved oxygen, fish kills, and major shellfish harvest areas.
Houtman
Houtman is a marine ecoregion of Western Australia's mid-west coast, covering the waters around the Houtman Abrolhos Islands, which hold the Indian Ocean's highest-latitude coral reefs.
Hudson Bay
Hudson Bay: large shallow seasonally ice-covered inland sea in central Canada, ~1.2 million km², receiving ~900 km³/yr river runoff; declining sea ice, isostatic rebound, Hudson's Bay Company history, polar bears, and Port of Churchill shipping.
Hudson Strait
Hudson Strait is a long channel in northern Canada, between Baffin Island and Quebec, linking Hudson Bay and Foxe Basin to the Labrador Sea; first recorded in 1578.
Hughes Bay
Hughes Bay, also Bahía Hughes, is a bay between Cape Sterneck and Cape Murray on the Danco Coast, west Antarctic Peninsula, named for sealer Edward Hughes (1824-25) and site of the first recorded Antarctic mainland landing by John Davis, 7 February 1821.
Humber
The Humber is England's largest-catchment macro-tidal estuary, formed by the Trent and Ouse, home to the UK's biggest port complex, over 500,000 people at tidal flood risk, and internationally important waterbird habitats.
Hunter Estuary
The Hunter Estuary is the tidal lower reach of the Hunter River in New South Wales, Australia, where it meets the Tasman Sea at Newcastle.
Huon Bay
Huon Bay is a shallow Antarctic bay about 8 miles wide between Cape Ducorps and Cape Legoupil on the northwest coast of Louis Philippe Peninsula, at 63°23'S 58°00'W, named by d'Urville's 1837-40 expedition for Félix Huon de Kermadec.
Iapetus Ocean
Iapetus Ocean, the proto-Atlantic paleo-ocean proposed by J. Tuzo Wilson in 1966, opened between Laurentia, Baltica, and Avalonia in the late Neoproterozoic and closed in the Silurian, forming the Caledonian–Appalachian orogen and the Iapetus suture.
Ice Cover
Ice cover: ice on oceans, lakes, rivers, and land (sea ice, freshwater ice, ice sheets). Sea ice covers ~9% of oceans; Arctic ice has thinned and shrunk sharply since 1979.
IJ (Amsterdam)
The IJ is Amsterdam's central waterway, once a Zuiderzee tidal bay, now running from the IJmeer to the North Sea Canal. Key facts: 1876 canal, GVB ferries, IJburg islands, IJmuiden salt management.
Inaccessible Island
Inaccessible Island: uninhabited 14 km² volcanic island in the Tristan da Cunha group, South Atlantic, part of the UK Overseas Territory of St Helena, Ascension and Tristan da Cunha; World Heritage Site since 2004, home of the Inaccessible Rail and Spectacled Petrel, with no introduced mammals.
Indian Ocean Basin mode
The Indian Ocean Basin mode (IOB) is the dominant pattern of year-to-year sea surface temperature variability in the tropical Indian Ocean, a basin-wide warming or cooling.
Indian Ocean Dipole
Indian Ocean Dipole (IOD), measured by the Dipole Mode Index, is a sea surface temperature seesaw between the western and eastern tropical Indian Ocean with positive, negative, and neutral phases, discovered by Saji et al. in 1999, affecting East African, Indonesian, and Australian rainfall.
Indian Ocean garbage patch
The Indian Ocean garbage patch is a poorly defined accumulation of floating plastic in the southern Indian Ocean subtropical gyre, southeast of Madagascar; unlike the Pacific and Atlantic patches it is weak, dispersive, and under-sampled, and no northern patch exists because land blocks the gyre.
Indian Ocean Geoid Low
The Indian Ocean Geoid Low (IOGL) is Earth's lowest geoid anomaly, a −106 m depression south of India caused by low-density mantle plume material generated when Tethyan slabs perturbed the African LLSVP.
Indian Ocean trade
Indian Ocean trade: maritime commerce linking East Africa, Arabia, Iran, India, Southeast Asia, and China from the Bronze Age onward, driven by monsoon winds, centered on Indian textiles and spices, and predating European entry by millennia.
Indian oil sardine
Indian oil sardine (Sardinella longiceps), a small tropical pelagic fish of the northern Indian Ocean and India's key sardine fishery, contributing 17–20% of national marine landings, centered on Kerala's Malabar upwelling zone.
Indonesian Throughflow
Indonesian Throughflow (ITF, Arus Lintas Indonesia): the only tropical interocean current, carrying warm, fresh Pacific water through Indonesian straits into the Indian Ocean at about 15 Sv, mainly via Makassar Strait, affecting ENSO and global climate.