Hydrographers, from centuries ago until today, have developed nautical charts to tell mariners where waters are safe. Back in the 16th century, charts showed the location of ghoulish "monsters," ready to devour complete vessels. Today, NOAA hydrographers search for modern monsters—undiscovered underwater geologic formations and other dangers to navigation.
There are nearly 3,500,000 square nautical miles of our nation’s waters to monitor, understand, and chart. The Office of Coast Survey evaluates the 500,000 square nautical miles that are navigationally significant. Then, each spring, hydrographic field parties set out to survey sections of the 43,000 square nautical miles deemed to be critical by the Coast Survey's evaluation. Sometimes teams break loose from normal surveying to respond to disasters such as hurricanes.