The ocean is the lifeblood of Earth, covering about 70 percent of the planet’s surface, driving weather, regulating temperature, and ultimately supporting all living organisms. Throughout history, the ocean has been a vital source of sustenance, transport, commerce, growth, and inspiration.
Yet for all of our reliance on the ocean, more than eighty percent of this vast, underwater realm remains unmapped, unobserved, and unexplored.
Given the high degree of difficulty and cost in exploring our ocean using underwater vehicles, researchers have long relied on technologies such as sonar to generate maps of the seafloor. Currently, less than ten percent of the global ocean is mapped using modern sonar technology. For the ocean and coastal waters of the United States, only about 35 percent has been mapped with modern methods.
NOAA’s Office of Ocean Exploration and Research is leading efforts to explore the ocean by supporting expeditions to investigate and document its unknown and little known regions. These expeditions are led by scientist-explorers equipped with the latest exploration tools.
Meanwhile, NOAA’s Office of Coast Survey explores the ocean in a different way, employing hydrographic surveys to generate nautical charts. Since the mid-1830s, the U.S. Coast Survey (a NOAA predecessor agency) has been the nation’s nautical chartmaker. Today, Coast Survey is still responsible for creating and maintaining all charts of U.S. coastal waters, the Great Lakes, and waters surrounding U.S. territories.
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Sonar, short for Sound Navigation and Ranging, is helpful for exploring and mapping the ocean because sound waves travel farther in the water than do radar and light waves. NOAA scientists primarily use sonar to develop nautical charts, locate underwater hazards to navigation, search for and map objects on the seafloor such as shipwrecks, and map the seafloor itself. There are two types of sonar—active and passive.
Last updated: 01/20/23
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