sea·​floor | \ ˈsē-ˌflȯr How to pronounce seafloor (audio) \
variants: or less commonly sea floor
plural seafloors also sea floors

Definition of seafloor

: the floor of a sea or ocean : seabed The Earth's crust, in this view, is divided into several immense plates that make up the continents and seafloors, and that all float on a hot, plastic, subterranean "mantle."— Walter Sullivan

Examples of seafloor in a Sentence

Recent Examples on the Web Corliss suspected that a volcano, what marine scientists call a hydrothermal vent, was erupting on the deep seafloor in the area. James Nestor, Scientific American, "Life on the Rocks," 12 Feb. 2018 Today, colonies of Archaea cluster around similarly nutrient-rich vents on the seafloor. Nikk Ogasa, ABC News, "Acidic volcanic lakes may have harbored early life," 31 Jan. 2021 This upgrade alone will extend Alvin’s maximum depth by more than a mile and put approximately 99 percent of the seafloor within its reach. Daniel Oberhaus, Wired, "The Oldest Crewed Deep Sea Submarine Just Got a Big Makeover," 21 Dec. 2020 Say there’s an earthquake below the seafloor just off a coastline. Scott K. Johnson, Ars Technica, "Seismic sound waves crossing the deep ocean could be a new thermometer," 26 Sep. 2020 With less seafloor volcanism, the midocean ridges would have been smaller, increasing the capacity of the oceans. Paul Voosen, Science | AAAS, "Slowdown in plate tectonics may have led to Earth’s ice sheets," 22 Dec. 2020 The estimate was based upon a seafloor sampling project off the coast of Australia that recovered sediment. Danielle Hall, Smithsonian Magazine, "The Top Ten Ocean Stories of 2020," 17 Dec. 2020 The slow slip of the oceanic slab into the mantle scraped a thick layer of seafloor sediments into a pile at the edge of the Eurasian plate—and this sandy layer would later be squeezed into rock and end up on the mountainous peaks. Science, "Why Mount Everest keeps changing its height," 8 Dec. 2020 Precise geometric monoliths have been observed on Mars and its moons, for example, as well as on the seafloor of earth. Josephine Livingstone, The New Republic, "Why We Love the Monolith," 3 Dec. 2020

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'seafloor.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of seafloor

1853, in the meaning defined above

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The first known use of seafloor was in 1853

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Last Updated

27 Feb 2021

Cite this Entry

“Seafloor.” Dictionary, Merriam-Webster, Accessed 2 Mar. 2021.

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English Language Learners Definition of seafloor

: the ground that is at the bottom of the sea

More from Merriam-Webster on seafloor

Nglish: Translation of seafloor for Spanish Speakers

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