877 articles
Overfalls
Overfalls are areas of rough, breaking sea caused by strong tidal currents over shoals, meeting currents, or wind against tide; a charted nautical hazard related to tide rips and tidal races.
Pacific decadal oscillation
Pacific decadal oscillation (PDO), related to the Interdecadal Pacific Oscillation (IPO), is a decadal-scale pattern of North Pacific sea surface temperature and pressure variability, defined by Mantua et al. 1997, with warm and cool phases affecting North American climate and fisheries.
Pacific hurricane
Pacific hurricane: a tropical cyclone in the eastern or central North Pacific reaching 74 mph winds; season May 15 to November 30, averaging 15 named storms, 8 hurricanes, 4 major hurricanes, boosted by El Niño.
Pacific Ocean
The Pacific Ocean, Earth's largest ocean, lies between the Americas and Asia-Australia, divided into North and South Pacific by convention. Key facts: Bering Strait is its only Arctic gateway (~1 Sv flow, rising since 1990), and IHO limits place its southern boundary at 60°S.
Pacific-Antarctic Ridge
Pacific-Antarctic Ridge: South Pacific mid-ocean ridge spreading center between the Pacific and Antarctic plates, with en echelon segments, a mantle boundary near the Easter microplate, and interaction with the Foundation hotspot.
Pactolus Bank
Pactolus Bank, also called Burnham Bank, is a reported submerged bank in the Southern Ocean west of Cape Horn, sounded in 1885 and never confirmed.
Palk Strait
Palk Strait (Paakku Niirinai, Pok Samudra Sandhiya) is the shallow 75-km-wide strait between Tamil Nadu, India, and northern Sri Lanka, named after Governor Sir Robert Palk, bounded by Adam's Bridge and central to the India–Sri Lanka trawling dispute.
Palmer Basin
Palmer Basin, also called Palmer Deep (US ACUF), is an undersea inner-shelf basin southwest of Anvers Island, Antarctic Peninsula, up to 1400 m deep, with three sub-basins, ODP Sites 1098/1099, named for Nathaniel B. Palmer.
Pamlico Sound
Pamlico Sound, North Carolina's large shallow lagoonal estuary behind the Outer Banks, largest lagoonal ecosystem in the US, 5,200 km², fed by the Tar-Pamlico and Neuse rivers, connected to the ocean by three inlets.
Panama Basin
Panama Basin: oceanic basin of the eastern equatorial Pacific, bounded by the Cocos, Carnegie, and Galapagos ridges; tectonically active, productive, hypoxic at 400 m; Gulf of Panama upwelling failed in 2025.
Panthalassa
Panthalassa, meaning "all water," was a vast global ocean surrounding Pangaea from the late Paleozoic into the early Mesozoic, with the Pacific Ocean as its modern remnant.
Paratethys
Paratethys was a vast shallow epicontinental sea that covered Eurasia's southern margin from about 33 million years ago into the Pliocene, leaving the Black, Caspian, and Aral seas.
Parece Vela Basin
Parece Vela Basin, also formerly called West Mariana Basin, is an extinct back-arc basin in the Philippine Sea Plate between the Kyushu-Palau and West Mariana ridges, formed about 30-15 Ma behind the proto Izu-Bonin-Mariana arc and hosting the Godzilla Megamullion, Earth's largest known oceanic core complex.
Parry Channel
Parry Channel is the deep east-west waterway of the Canadian Arctic Archipelago, the northern Northwest Passage route through M'Clure Strait, Viscount Melville Sound, Barrow Strait, and Lancaster Sound, named for explorer William Edward Parry.
Pearl Harbor
Pearl Harbor (Pu'uloa, Wai Momi) is a sheltered estuary on O'ahu, Hawai'i, home to Joint Base Pearl Harbor-Hickam; developed as a US naval base from 1902 and attacked by Japan on December 7, 1941.
Periplus of the Erythraean Sea (Περίπλους τῆς Ἐρυθρᾶς Θαλάσσης)
Periplus of the Erythraean Sea (Periplus Maris Erythraei): anonymous Greek merchant's handbook of the mid-1st century CE describing Red Sea, Arabian, and Indian Ocean trade routes, ports, and commodities, preserved in a single Heidelberg manuscript.
Persian Gulf (الخليج الفارسي)
The Persian Gulf (الخليج الفارسي), also called Arabian Gulf in some Arab countries, is a shallow sea between Iran and the Arabian Peninsula, about 1,000 km long, draining via the Strait of Hormuz and carrying major world oil exports.
Peru Basin
Peru Basin (Peruanisches Becken, Peruvian Basin): abyssal plain in the southeastern Pacific off Peru, 4,000-4,400 m deep, bounded by the Carnegie and Nazca Ridges, rich in manganese nodules and site of the 1989 DISCOL deep-sea mining disturbance experiment.
Peru–Chile Trench
Chile Trench (Peru–Chile Trench): 6,000-km oceanic trench off Chile and Peru where the Nazca Plate subducts beneath South America; Atacama Trench section exceeds 8,000 m depth; source of the 1960 Valdivia M9 earthquake.
Peter the Great Gulf (Залив Петра Великого)
Peter the Great Gulf (Залив Петра Великого), also called Peter the Great Bay, is a large gulf on Russia's southern Primorsky Krai coast in the Sea of Japan, extending 185 km from the Tumen River to Cape Povorotny, containing Vladivostok, freezing December to mid-April, and claimed by Russia as a historical bay.
Petroleum exploration in the Arctic
Petroleum exploration in the Arctic covers oil and gas exploration in Arctic Alaska, the Chukchi and Beaufort Seas, Greenland, and Norway, marked by large USGS resource estimates, Shell's failed Chukchi wells, shifting U.S. leasing policy, and severe oil-spill response limits.
Philippine Sea
The Philippine Sea is the world's largest marginal sea, about 5 million km², east of the Philippine archipelago in the western Pacific. Its floor is the Philippine Sea Plate, ringed by subduction zones and the source region of many typhoons.
Philippine Trench
Philippine Trench, also once called Emden Trench: a 1,571 km subduction trench east of the Philippines where the Philippine Sea plate descends westward; deeper than 10,000 m and a major tsunamigenic zone.
Pico Island (island, Portugal)
Pico Island (Ilha do Pico), second largest of Portugal's nine Azores islands, 447.9 km², holds Mount Pico at 2,351 m, Portugal's highest point, and the UNESCO-listed basalt-walled vineyard landscape inscribed in 2004.
Pillars of Hercules
Pillars of Hercules (Ἡράκλειαι Στῆλαι), ancient name for the Strait of Gibraltar and its flanking promontories, Calpe (Gibraltar) and Abila; also bronze columns of Melqart at Gades, marking the world's western edge.
Piper Alpha
Piper Alpha was an oil and gas production platform in the UK North Sea, destroyed by explosions and fire on 6 July 1988, killing 167 of the 226 men aboard.
Piracy in the Strait of Malacca
Piracy in the Strait of Malacca is armed robbery against ships in the 930 km waterway between the Malay Peninsula and Sumatra, peaking with 28 attacks in 2003.
Piracy off the coast of Somalia
Piracy off the coast of Somalia, or Somali piracy, is ransom-driven hijacking in the Gulf of Aden and western Indian Ocean that emerged after Somalia's 1991 state collapse, peaked in 2011, was suppressed by 2012, and resurged from 2024.
Pitman Fracture Zone
Pitman Fracture Zone, formerly Fracture Zone XII, a right-stepping fracture zone on the Pacific-Antarctic Ridge at about 65 degrees S; initiated at chron C27, named for Walter C. Pitman III, records 65 Myr of plate motion and late Neogene transtension.
Pittwater
Pittwater is a tide-dominated drowned river valley estuary north of Sydney, NSW, connected to the Hawkesbury River; 18.4 km², average depth 9.9 m, named by Governor Phillip in 1788, formerly governed by Pittwater Council (1992–2016).