Wessel et al. (2010) highlight the need for a systematic mapping of seamounts in ocean basins. They estimate that 100,000 or 90% of the seamounts greater than 1-km tall are unobserved by either ship soundings or satellite gravity. There are two reasons why most of these relatively large, predicted seamounts remain uncharted. First, satellite-derived gravity is only able to reliably measure seamounts that are more than 2-km tall, although smaller seamounts can be detected (Wessel, 2001). Second, the freely available ship sounding data collected during the past 50 years only covers 10% of the seafloor at the 1-minute resolution needed to detect these 1-km and taller seamounts (Becker et al., 2009). Based on current trends in seafloor mapping, the rate of seamount discoveries is not likely to change significantly because modern research surveys are focused on particular areas of high scientific interest such as mid-ocean ridges, continental margins, and subduction zones. This exploration strategy has resulted in gaps in remote areas of up to 600 km by 300 km. As Figure 1 shows, more than 50% of the seafloor lies more than 9.5 km from the nearest ship sounding. This sparse coverage, combined with a relatively random spatial distribution of seamounts, results in the situation today where there are even 3-km and 4-km tall seamounts that have not been surveyed by ships.

Sandwell, D.T., and P. Wessel. 2010. Box 3: Seamount discovery tool aids navigation to uncharted seafloor features. Oceanography 23(1):34–36, https://doi.org/10.5670/oceanog.2010.87.

Becker, J.J., D.T. Sandwell, W.H.F. Smith, J. Braud, B. Binder, J. Depner, D. Fabre, J. Factor, S. Ingalls, S.-H. Kim, and others. 2009. Global bathymetry and elevation data at 30 arc seconds resolution: SRTM30_PLUS. Marine Geodesy 32(4):355–371, https://doi.org/10.1080/01490410903297766.
1. Hammond, S., J. McDonough, and C. Russell. 2010. Box 5: The NOAA ship Okeanos Explorer: New ways for exploring the ocean. Oceanography 23(1):88–89.
2. Smith, W.H.F., and D. Sandwell. 1997. Global seafloor topography from satellite altimetry and ship depth soundings. Science 277:1,956–1,962.
3. Wessel, P. 2001. Global distribution of seamounts inferred from gridded Geosat/ERS-1 altimetry. Journal of Geophysical Research 106(B9):19,431–19,441.
4. Wessel, P., D.T. Sandwell, and S.-S. Kim. 2010. The global seamount census. Oceanography 23(1):24–33.

This is an open access article made available under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution, and reproduction in any medium or format as long as users cite the materials appropriately, provide a link to the Creative Commons license, and indicate the changes that were made to the original content. Images, animations, videos, or other third-party material used in articles are included in the Creative Commons license unless indicated otherwise in a credit line to the material. If the material is not included in the article’s Creative Commons license, users will need to obtain permission directly from the license holder to reproduce the material.