Isobath or bathymetric contour or depth contour for the delineation itself or alternatively, bathymetric or hydrographic for the chart -


http://www.merriam-webster.com/dictionary/isobath

Full Definition of ISOBATH
1
: an imaginary line or a line on a map or chart that connects all points having the same depth below a water surface (as of an ocean, sea, or lake)
2
: a line similar to an isobath indicating depth below the earth's surface of an aquifer or other geological horizon

Origin of ISOBATH
ISV is- + -bath (fr. Gk bathos depth); akin to Gk bathys deep — more at bathy-


http://en.wikipedia.org/wiki/Bathymetry

Bathymetric (or hydrographic) charts are typically produced to support safety of surface or sub-surface navigation, and usually show seafloor relief or terrain as contour lines (called depth contours or isobaths) and selected depths (soundings), and typically also provide surface navigational information. Bathymetric maps


http://www.gmat.unsw.edu.au/ablos/ABLOS01Folder/Jakobsson_et...

P. 1

The uncertainty of a bathymetric contour: implications for the cut-off line

Abstract

We have addressed the question of variability of isobaths derived from bathymetric grid models by investigating how the random errors in the source data propagate through the gridding process to the final derived isobath by the use of a Monte Carlo simulation method. We have focused this experiment on the 2500 m isobath derived from a subset of the International Bathymetric Chart of the Arctic Ocean (IBCAO) around Svalbard...

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Note added at 1 hr (2014-03-30 07:47:31 GMT)
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From the U.S. Energy Information Administration -


http://www.eia.gov/countries/regions-topics.cfm?fips=scs

South China Sea

Brunei

According to Malaysia, the 1958 U.K. Order in Council set the proper maritime boundary between Brunei and Malaysia (when both countries were British territories) at the 100-fathom isobaths from the coast. Despite the lack of any formal claims, Brunei's continental shelf claim implies ownership of the Louisa Reef, which is technically part of the Spratly Islands archipelago.


From the Russian Academy of Sciences and the Woods Hole Oceanographic Insitute, Massachusetts -


http://www.deepseadrilling.org/42_2/volume/dsdp42pt2_47.pdf

Black Sea Geophysical Framework

Based on the bathymetric data, the Black Sea can be divided into four principal physiographic provinces (Figure 3): 1) Shelf - generally delineated by the 100 meter isobath except off the Crimean peninsula and Sea of Azov where it extends to 130 meters...


From Encyclopaedia Iranica -


http://www.iranicaonline.org/articles/caspian-sea-i



CASPIAN SEA i. GEOGRAPHY

...

There are important differences in the prevailing water temperatures at different longitudes. In the north, although surface temperatures rise to 24° C in summer, in winter, which generally lasts from December to March, the sea freezes down to approximately isobath - 12 m. Ice floes can appear as far south as Derbent (Darband).