Bathymetric chart

A bathymetric chart is the submerged equivalent of an above-water topographic map. Bathymetric charts are designed to present accurate, measurable description and visual presentation of the submerged terrain. A bathymetric chart is the submerged equivalent of an above-water topographic map. Bathymetric charts are designed to present accurate, measurable description and visual presentation of the submerged terrain. Bathymetric surveys and charts are more closely tied to the science of oceanography, particularly marine geology, and underwater engineering or other specialized purposes. Bathymetric charts can also be converted to bathymetric profiles. A bathymetric chart differs from a hydrographic chart in that accurate presentation of the underwater features is the goal, while safe navigation is the requirement for the hydrographic chart. A hydrographic chart will obscure the actual features to present a simplified version to help mariners avoid underwater hazards. In an ideal case, the joining of a bathymetric chart and topographic map of the same scale and projection of the same geographic area would be seamless. The only difference would be that the values begin increasing after crossing the zero at the designated sea level datum. Thus the topographic map's mountains have the greatest values while the bathymetric chart's greatest depths have the greatest values.