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Survey vessel
A survey vessel, also called a survey ship, is a ship or boat fitted with sonar for measuring water depth and mapping the seafloor for nautical charts.
Surveying Ships' Squadron
The Surveying Ships' Squadron was the Royal Navy's organized flotilla of hydrographic surveying ships, the direct descendant of the Surveying Service founded in 1817 within the Admiralty's Hydrographic Department.
Suspended load
Suspended load is the part of a river's sediment load supported by turbulence and carried downstream at roughly the water's velocity, unlike bedload, which moves along the streambed.
Suswa
Suswa (Mount Suswa) is a Quaternary peralkaline trachyte-phonolite shield volcano in the Kenyan Rift, ~50 km WNW of Nairobi, with nested 8 x 12 km and 5 km calderas, Ol Doinyo Onyoke cone, geothermal activity, and no recorded historical eruption.
Suture zone
A suture zone is the geological boundary where two tectonic plates once separated by an ocean collided and welded together, marked by ophiolites and deformed rocks.
Sverdrup (unit)
The sverdrup (Sv) is a non-SI oceanography unit of volume transport equal to one million cubic meters per second, named for Norwegian oceanographer Harald Ulrik Sverdrup.
Swash
Swash is the sheet of water that runs up a beach after a wave breaks and flows back down; the strip of beach it moves over is the swash zone.
SWAT model
The SWAT model, or Soil and Water Assessment Tool, is a USDA river basin model that predicts how land management affects water, sediment, and chemical yields in watersheds.
SWAT+
SWAT+ (Soil and Water Assessment Tool Plus) is a public-domain watershed model simulating water quantity and quality from small watersheds to large river basins, developed by USDA-ARS and Texas A&M AgriLife Research.
Swedish Meteorological and Hydrological Institute
The Swedish Meteorological and Hydrological Institute (SMHI, Sveriges meteorologiska och hydrologiska institut) is a Swedish government agency for weather, water, and climate information, founded in 1945.
Swell (ocean)
Swell, also called ocean swell, is a set of wind-generated ocean waves that have traveled out of their generating area, showing smoother, longer-period crests than wind waves.
SWOT (satellite)
SWOT (Surface Water and Ocean Topography) is a NASA and CNES satellite launched in December 2022 that makes the first global survey of Earth's oceans, lakes, and rivers.
Syenite
Syenite is a coarse-grained plutonic igneous rock composed mainly of alkali feldspar with little or no quartz, the quartz-poor counterpart of granite, named after Syene, Egypt.
Synchrotron X-ray tomography
Synchrotron X-ray tomography is a non-destructive imaging method that reconstructs the 3D internal structure of a sample from hundreds of synchrotron X-ray radiographs, at micrometer or finer resolution within minutes.
Syncline
A syncline is a downward fold in layered rocks in which the youngest strata occupy the core, the counterpart of the anticline, whose core holds the oldest rocks.
SYNOP
SYNOP, or surface synoptic observations, is the World Meteorological Organization code for reporting surface weather from land stations, exchanged worldwide to build a synoptic picture for forecasting.
Systema Naturae
Systema Naturae is Carl Linnaeus's classification of minerals, plants, and animals, first published in Leiden in 1735 as an 11-page folio; its 10th edition (1758) starts zoological nomenclature and named Homo sapiens.
Systems tract
A systems tract is a linkage of contemporaneous depositional systems, defined by its position in a depositional sequence; it was introduced by Brown and Fisher in 1977.
Taal Volcano
Taal Volcano is an active complex caldera volcano in Batangas province on Luzon, Philippines, whose caldera holds Taal Lake and Volcano Island, the site of its recent eruptions.
Taam Ja' Blue Hole
The Taam Ja' Blue Hole is a submarine sinkhole in Chetumal Bay, Mexico, and the deepest known blue hole, measured to 423.6 meters with its bottom unreached.
Taiga
The taiga, also called the boreal forest, is the belt of conifer forest across northern North America and Eurasia south of the tundra, holding 27 percent of the world's forest area.
Tailings
Tailings, also called mine tailings, are the crushed rock and processed fluids left after ore is milled and valuable minerals removed, generating about 13 billion tonnes of wet slurry waste yearly.
Talang
Talang (Gunung Talang) is an active 2,575-2,597 m stratovolcano in West Sumatra, Indonesia, on the Great Sumatran Fault; phreatic eruptions in 2005 and 2007, alert lowered to level 1 in January 2026.
Talik
A talik, from a Siberian word introduced to science by Siemon W. Muller in 1945, is ground that stays unfrozen year-round within permafrost, moving water and heat through frozen ground.
Tanami Mine
The Tanami Mine is a large underground gold mine in the remote Tanami Desert of the Northern Territory, Australia, owned and operated by Newmont since 2002.
Tangkuban Perahu
Tangkuban Perahu, also spelled Tangkuban Parahu, is an active 2,084 m stratovolcano in West Java, Indonesia, north of Bandung, known for small phreatic eruptions and tourism.
Tanzanite
Tanzanite, also known as blue zoisite, is a violet blue gem variety of zoisite found only in Tanzania's Merelani Hills and named by Tiffany & Co. in 1968.
Tar pit
A tar pit, also known as an asphalt seep, is a natural accumulation of asphalt formed when petroleum seeps upward and loses volatile components, trapping and preserving animals.
Tara Oceans
Tara Oceans was a 2009–2013 oceanographic expedition aboard the 36 m schooner Tara that sampled plankton across the world's oceans, co-directed by Eric Karsenti and Etienne Bourgois.
Tasiast mine
The Tasiast mine is an open-pit gold mine in north-western Mauritania, about 300 km north of Nouakchott, owned by Canada's Kinross Gold since 2010 and producing 622,000 ounces of gold in 2024.