Editing Bathymetry (section)

{{Short description|Study of underwater depth of lake or ocean floors}}
[[File:Mid-ocean ridge system.gif|thumb|upright=1.7| {{center|Bathymetry of the ocean floor showing the [[continental shelf|continental shelves]] and [[oceanic plateau]]s (red), the [[mid-ocean ridge]]s (yellow-green) and the [[abyssal plain]]s (blue to purple)}}]]
[[File:Draining the Oceans video by NASA.webm|thumb|right|Animation reveals oceanic floors and seabeds. [[Continental shelves]] appear mostly by a depth of 140 meters, [[mid-ocean ridge]]s by 3000 meters, and [[oceanic trench]]es at depths beyond 6000 meters.]]
[[File:Map_of_ocean_floor_based_on_earths_gravity_field.png|thumb|right|A seafloor map captured by NASA]]

'''Bathymetry''' ({{IPAc-en|b|ə|'|θ|ɪ|m|ə|t|r|i}}; {{etymology|grc|''{{wikt-lang|grc|βαθύς}}'' ({{grc-transl|βαθύς}})|deep||''{{wikt-lang|grc|μέτρον}}'' ({{grc-transl|μέτρον}})|measure}})<ref>[https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dbaqu%2Fs βαθύς], Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus</ref><ref>[https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dme%2Ftron μέτρον], Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus</ref> is the study of underwater depth of [[seabed|ocean floors]] (''[[seabed topography]]''), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to [[hypsometry]] or [[topography]]. The first recorded evidence of water depth measurements are from [[Ancient Egypt]] over 3000 years ago.<ref name="wolfl2019">{{cite journal | last1 = Wölfl | first1 = A.C. | last2 = Snaith | first2 = H. | last3 = Amirebrahimi | first3 = S. | display-authors = etal | title = Seafloor Mapping – The Challenge of a Truly Global Ocean Bathymetry | journal = Frontiers in Marine Science | date = 2019 | volume = 6 | doi = 10.3389/fmars.2019.00283 | page = 283| doi-access = free | bibcode = 2019FrMaS...6..283W }}</ref> Bathymetry has various uses including the production of [[bathymetric charts]] to guide vessels and identify underwater hazards, the study of [[Bottom feeder|marine life near the floor of water bodies]], coastline analysis and [[ocean dynamics]], including predicting currents and tides.<ref>{{Cite web |title=How is bathymetric data used? |author= |work=[[National Oceanic and Atmospheric Administration]] |date= |access-date=16 December 2024 |url= https://oceanservice.noaa.gov/facts/bathyuses.html}}</ref>

Bathymetric charts (not to be confused with ''[[hydrographic chart]]s''), are typically produced to support safety of surface or sub-surface navigation, and usually show seafloor relief or [[terrain]] as [[contour line]]s (called ''[[depth contours]]'' or ''[[isobaths]]'') and selected depths (''[[Depth sounding|soundings]]''), and typically also provide surface [[navigation]]al information.  Bathymetric maps (a more general term where navigational safety is not a concern) may also use a [[Digital Terrain Model|digital terrain model]] and artificial illumination techniques to illustrate the depths being portrayed. The global bathymetry is sometimes combined with topography data to yield a [[global relief model]]. '''Paleobathymetry''' is the study of past underwater depths.

Synonyms include '''seafloor mapping''', '''seabed mapping''', '''seafloor imaging''' and '''seabed imaging'''. Bathymetric measurements are conducted with various methods, from [[depth sounding]], [[sonar]] and [[lidar]] techniques, to [[buoy]]s and [[satellite altimetry]]. Various methods have advantages and disadvantages and the specific method used depends upon the scale of the area under study, financial means, desired measurement accuracy, and additional variables. Despite modern computer-based research, the ocean seabed in many locations is less measured than the [[topography]] of [[Mars]].<ref>{{cite book|last1=Jones|first1=E.J.W.|title=Marine geophhysics|date=1999|publisher=Wiley|location=New York}}</ref>