What is Hydrographic Surveying?

Hydrographic Survey is an instrumental survey to measure and determine characteristics of streams and other bodies of water extent, and depth of water in lakes or the ocean; the width, depth, and course of streams; position and elevation of high water marks; location and depth of wells, etc.
Global Positioning Systems (GPS) on board ship can be used to determine the horizontal position of the surveyed point.

LSGI students use an Echo sounder to find the depth of the sea bed