Hydrographic survey is the process of gathering information about navigable waters for the purposes of safe navigation of vessels. It strictly applies to survey of any navigable waters, including lakes and rivers, but it is most commonly applied to marine navigation.

Hydrography is collected under strict rules for evaluating and positioning the data so that it may be accurately charted. Data will include shore features of use to navigators as well as information about the waters and bottom. Traditionally conducted by vessels and with Echo sounding, surveys are increasingly conducted with the aid of aircraft and sophisticated electronic sensor systems in shallow waters.

Surveys are most most commonly conducted by or under the supervision of national organizations with responsibility for chart making and distribution. Coordination of those organizations voluntarily joined with the goal of improving hydrography and safe navigation is conducted by the International Hydrographic Organization.

• NOAA's Hydrographic Website