877 articles
Riiser-Larsen Ice Shelf embayments of the Weddell margin
The Riiser-Larsen Ice Shelf embayments of the Weddell margin are coastal indentations along Antarctica's Weddell Sea, notably Vahsel Bay, charted in 1912, and the Lassiter Coast.
Ring of Fire
Ring of Fire (Pacific Ring of Fire): popular name for the circum-Pacific belt of subduction-zone volcanoes and earthquakes, not a scientific term. Holds 687 Holocene volcanoes (57% of world total) and about 81% of the largest earthquakes; first named by Carl Ritter in 1859.
Río de la Plata
Río de la Plata (River Plate): funnel-shaped microtidal estuary between Argentina and Uruguay, 300 km long and up to 220 km wide, draining the Paraná and Uruguay rivers into the South Atlantic; one of the world's most turbid estuaries.
Rio Grande Rise
Rio Grande Rise: large submerged volcanic plateau in the SW Atlantic, ~1,000-1,200 km off Brazil, conjugate of the Walvis Ridge, formed by 30+ Myr of Tristan-Gough plume-ridge interaction, with ferromanganese crusts of critical minerals.
Roadstead
Roadstead, also road or roads, an area of sea near shore where vessels anchor and transfer cargo with less shelter than a harbor; part of the territorial sea under UNCLOS Article 12, not inland waters.
Robeson Channel
Robeson Channel (Détroit de Robeson) is a 57-mile Arctic waterway between Greenland and Ellesmere Island, the northernmost and narrowest part of Nares Strait and a major sea-ice export gate.
Rockpepper Bay
Rockpepper Bay (Ensenada Güemes) is a bay at 63°08'S, 55°45'W on the northern coast of Joinville Island, Antarctic Peninsula, named for its many off-shore rocks and islets; variant name Elsie Bay.
Roebuck Bay
Roebuck Bay (Yawuru Nagulagun) is a tropical embayment at Broome, Western Australia, a 1990 Ramsar site of 34,141 ha with 9 m tides, 160 km2 of mudflats, and over 300,000 migratory shorebirds annually.
Röhss Bay
Röhss Bay is a bay 11 nautical miles wide on the southwest side of James Ross Island, Antarctica, between Cape Broms and Cape Obelisk, discovered by the Swedish Antarctic Expedition of 1901–04.
Ronne Entrance
Ronne Entrance, formerly Ronne Bay, is the broad southwestern entrance of George VI Sound opening onto the Bellingshausen Sea, West Antarctica. Discovered December 1940 by Finn Ronne and Carl Eklund; renamed as bay ice receded.
Ross Gyre
Ross Gyre: cyclonic subpolar ocean gyre south of the Antarctic Circumpolar Current in the southwest Pacific, near the Ross Sea. Wind-driven circulation of roughly 20–45 Sv, area about 1.84 million square kilometers, affecting dense-water formation.
Ross Sea
The Ross Sea is a Pacific Ocean bay between Cape Adare and Cape Colbeck, discovered by James Clark Ross in 1841. It is administered by New Zealand.
Russian Arctic islands
Russian Arctic islands: Franz Josef Land, Novaya Zemlya, Severnaya Zemlya, the New Siberian Islands, and Wrangel Island, Arctic Ocean archipelagos totaling over 180,000 km², largely glaciated, depopulated, militarized, and partly protected as national park and UNESCO reserve.
Sacheon (사천)
Sacheon (사천, 泗川市) is a rural-urban city in southwestern South Gyeongsang Province, South Korea, formed in 1995 by merging Samcheonpo City and Sacheon County; Sacheon Bay splits it, with fisheries, aerospace industry, and 108,504 residents in 2024.
Sacramento–San Joaquin River Delta
Sacramento–San Joaquin River Delta: inverted tidal freshwater delta and West Coast's largest estuary in central California; hub of California water system serving two-thirds of the state, with subsided leveed islands, SWP/CVP exports, Delta smelt controversy, and Delta Conveyance tunnel project.
Saginaw Bay
Saginaw Bay, a large shallow embayment of western Lake Huron in Michigan fed by the Saginaw River, known for its historic lumber era, walleye fishery, and Area of Concern contamination and restoration.
Sakhalin Gulf
Sakhalin Gulf (Sakhalinski Zaliv), a gulf of the Sea of Okhotsk between mainland Russia and the Schmidt Peninsula of northern Sakhalin Island, up to 160 km wide, ice-covered mid-November to late April, receiving most Amur River discharge.
Saldanha Bay
Saldanha Bay is a large natural bay on South Africa's west coast, about 100 km north of Cape Town, and the country's largest and deepest natural bay.
Salish Sea
Salish Sea: official umbrella name (approved 2009-2010) for the inland waters of Juan de Fuca Strait, Strait of Georgia, and Puget Sound, spanning British Columbia and Washington; about 18,000 sq km, Coast Salish homeland, estuarine ecosystem of roughly 8.7 million people.
Saltstraumen
Saltstraumen: tidal current between Straumøya and Godøya in Bodø, Norway, connecting Saltfjorden and Skjerstadfjorden; regarded as the world's strongest tidal current, with 20-knot peaks, 10 m whirlpools, and a 24.7 km² marine protected area.
Samar Sea
Samar Sea, small semi-enclosed Philippine sea between southern Luzon and Eastern Visayas, bordered by Samar, Leyte, Masbate; 3,870 sq km, overfished since the 1980s, site of first Philippine red tide in 1983.
San Bernardino Strait
San Bernardino Strait separates Samar from southeastern Luzon in the Philippines, linking the Philippine Sea with the Samar Sea. Sill depth 80 m; Manila Galleon route; Kurita's 1944 Leyte Gulf passage.
San Diego Bay
San Diego Bay is a crescent-shaped natural harbor in southern California, 18 miles long behind the Silver Strand. Entered by Cabrillo in 1542, settled in 1769, managed since 1962 by the Port of San Diego, and home to the Navy's Third Fleet.
San Francisco Bay
San Francisco Bay is the largest Pacific estuary in the Americas, a 1,600-square-mile tidal estuary where the Sacramento and San Joaquin Rivers meet the Pacific through the Golden Gate, shaped by ice-age filling, Gold Rush sediment, and modern restoration.
San Matías Gulf
San Matías Gulf (Golfo San Matías), Argentina's large semi-enclosed Patagonian gulf between Río Negro and Chubut, about 19,700 km², tide-dominated, high salinity, right whale habitat, and site of contested LNG and oil export projects.
Santa Cruz Basin
Santa Cruz Basin: deep (1,900 m) intermediate basin of the California Continental Borderland south of the Channel Islands; slumping, canyon-fed sedimentation, up to 4 km Miocene subsidence, gas hydrate BSR. Not the Arizona groundwater basin or central California Tertiary basin.
Santo Antão
Santo Antão (Ilha de Santo Antão), Cape Verde's westernmost and northernmost island: 779 km², Tope da Coroa 1,979 m, about 44,000 people, three municipalities, reached only by ferry from Mindelo; a mountainous hiking and farming island, not the Brazilian city Vitória de Santo Antão.
Sararken Ridges
Sararken Ridges (formerly Sararken Ridge) is an undersea ridge feature in Indonesian waters named for the Papuan word for octopus, adopted into the IHO-IOC GEBCO Gazetteer at SCUFN-38 in Bali, November 2025.
Sargasso Sea
The Sargasso Sea, within the North Atlantic Subtropical Gyre, is the only sea without a land boundary, bounded by the Gulf Stream, North Atlantic, Canary, and Equatorial Currents and covered in holopelagic Sargassum.
Saronic Gulf (Σαρωνικός κόλπος)
The Saronic Gulf is a semi-enclosed embayment of the Aegean Sea that serves as the marine gateway for Athens and Piraeus. It holds islands like Salamis and Aegina and is a major sailing area.