Per Oxford Dictionary of Earth Sciences: Seamounts are isolated, submarine mountain rising more than 1000m above the ocean floor. The sharp, crested summits of seamounts are usually 1000-2000m below the ocean surface. Seamounts are of volcanic origin.

Per kaberett: To avoid classifying seamounts by arbitrary sea level (dependent on availability of surface water), the key point is then that seamounts are features of volcanic origin that rise over 1000m above oceanic crust.

Per Wikipedia: A seamount is a mountain rising from the ocean seafloor that does not reach to the water's surface (sea level), and thus is not an island.

Per Oxford Dictionary: Submarine means "Existing, occurring, done, or used under the surface of the sea."

Per NOAA: A seamount is an underwater mountain on the seafloor.

Are all seamounts below the water, or do they include formations that rise above the water?

UPDATE: Atolls not within the scope of defining formations that rise above the water; meaning atolls are atolls, and not seamount crests.

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    $\begingroup$ Yes, they are all under the surface, as your research shows. Why this question? $\endgroup$ May 7 '14 at 16:14
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    $\begingroup$ just for clarity, we're not including seamounts which may have subsided and are now below the sea surface but have formed atolls which break the surface? $\endgroup$
    – Siv
    May 7 '14 at 16:48
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    $\begingroup$ You ask "What is a seamount" but already give a number of alternate answers yourself. Answers can merely give yet more definitions. I think this question appears to solicit debate, therefore I am closing. Feel free to edit the question to address my concerns. $\endgroup$
    – gerrit
    May 7 '14 at 17:28
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    $\begingroup$ @blunders No, it's not off-topic. It's unclear. I'm saying your question is unclear because you already give five alternate answers yourself, some more authoritative than others. What would make you accept yet another definition when these five do not answer your question? $\endgroup$
    – gerrit
    May 7 '14 at 17:34
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    $\begingroup$ @blunders Ok, then ask what definition is used by the largest utilised databases of seamounts? $\endgroup$
    – gerrit
    May 7 '14 at 18:36

A seamount is, quite simply:

an underwater mountain rising above the ocean floor

The term, however, does not have scientific consensus.

Some definitions include only formations over 1km in height, while some include formations as short as 100m. Some definitions say that the formation must be exclusively underwater, while other definitions include the the rise of the formation above the sea floor, even to the point of forming an island. Some definitions even include islands within the definition of seamount.

In the end, a "seamount" has to be defined within each study that uses it, since there is no consensus on whether to include super-surface formations.

  • $\begingroup$ Just realized your source for what a seamount is a "Quizlet.com - 5th Grade Science Vocabulary Sheet" link. Funny... :-) $\endgroup$
    – blunders
    May 7 '14 at 18:51
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    $\begingroup$ Hehe. :) I thought it was a nice counterpoint to the two previous answers with these large walls of text. $\endgroup$
    – Richard
    May 7 '14 at 18:58
  • $\begingroup$ Decide to select your answer as the answer, since it not only addresses the question, but is funny too; would up vote it too, but out of votes for today... :-) $\endgroup$
    – blunders
    May 7 '14 at 19:06

Staudigel et al. (2010):

The term seamount has been defined many times (e.g., Menard, 1964; Wessel, 2001; Schmidt and Schmincke, 2000; Pitcher et al., 2007; International Hydrographic Organization, 2008; Wessel et al., 2010) but there is no “generally accepted” definition. Instead, most definitions serve the particular needs of a discipline or a specific paper. [...] As we explore the major differences among definitions of the term “seamount,” several important issues play a role:

  • The inclusion of the temporarily emergent portions of seamounts is relatively obvious for geologists who look at seamount construction over long time scales. Many large seamounts either have summit regions that currently breach sea level, or at some point they emerged and are now entirely submerged. Hence, temporary emergence is part of the life cycle of many very large seamounts. The inclusion of emerged summits, however, is counter intuitive for a biologist. Biological communities on land are dramatically different from submerged communities and, hence, data from the emerged fractions of a seamount cannot be reasonably included into a focused marine biological study. The complexity of this issue is illustrated by Lō'ihi Seamount (see Spotlight 3 on page 72 of this issue [Staudigel et al., 2010]), an entirely submerged seamount that is located on the submarine flank of Mauna Loa, the largest volcano of the Hawaiian Islands.


  • Some seamount definitions also include aspects of their shape, in particular, restricting their use to conical features, whereby flat-topped (“tablemount”) seamounts are commonly called guyots. This morphological distinction is significant insofar as flat-topped seamounts are likely to once have been islands or coral reefs, while conical ones are likely to not to have breached the sea surface during their life cycle (Staudigel and Clague, 2010).
  • In their original definition, seamounts were defined based on their tectonic setting, specifically, as features on the seafloor that are not part of mid-ocean ridges or subduction zones (Menard, 1964). This limitation to intraplate volcanoes pays tribute to the distinct magmatic processes that form volcanoes at mid-ocean ridges, arc volcanoes, and in intraplate settings. Apparent exceptions are mantle hotspots located at or close to mid-ocean ridges, such as the one presumed to exist under Axial Seamount at the Juan de Fuca Ridge (see Spotlight 1 on page 38 of this issue [Chadwick et al., 2010]) that appears to be the origin of the Cobb seamount chain. Wessel et al. (2010) restrict their use of the term seamount to intraplate features, excluding arc volcanoes in their seamount count.

Full citation: Staudigel, H., A.A.P. Koppers, J.W. Lavelle, T.J. Pitcher, and T.M. Shank. 2010. Box 1: Defining the word "seamount". Oceanography 23(1):20–21, http://dx.doi.org/10.5670/oceanog.2010.85.


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