U.S. Navy

Surveying Ships (AGS / T-AGS)

Ships that map the invisible landscape beneath the ocean's surface — the mountains, canyons, and plains of the seafloor that determine where submarines can hide, where cables can be laid, and where amphibious forces can land. The tradition stretches from Matthew Fontaine Maury's first ocean charts in 1842 through WWII's classified thermocline maps that helped submarines evade detection, to the Cold War SOSUS network that tracked Soviet submarines by exploiting the deep sound channel. Today's Pathfinder-class survey ships carry multibeam sonar that maps the bottom in three-dimensional detail, operated by civilian mariners under the Military Sealift Command. The data they collect is the foundation of undersea warfare, and the nations that contest the world's oceans know exactly how valuable it is.

Pioneers — Charting the Unknown 1842 - 1945

Matthew Fontaine Maury

Father of Modern Oceanography

Naval Observatory

Physical Geography

Before Matthew Fontaine Maury, the ocean was a mystery that sailors crossed by dead reckoning and prayer. As superintendent of the U.S. Naval Observatory, Maury collected thousands of ships' logs and plotted the winds, currents, and depths of every ocean on earth. His 1855 work The Physical Geography of the Sea was the first comprehensive study of oceanography. He charted the Atlantic floor and identified the plateau where the first transatlantic telegraph cable would be laid. A Navy lieutenant who couldn't go to sea after a stagecoach accident crippled his leg, so he mapped the seas from his desk — and changed navigation forever. Read more

Explore Collection

WWII Oceanographic Intelligence

Thermoclines, Submarines, and the Hidden War

Layer Detection

Anti-Sub Warfare

Bathythermograph

World War II turned oceanography from academic curiosity into a weapon. Navy scientists discovered that thermoclines — layers of water at different temperatures — could bend and reflect sonar, creating invisible cloaks for submarines. Survey ships mapped ocean temperatures at depth, producing classified charts that told submarine captains exactly where to hide beneath the thermal layer and told destroyer crews where to aim their depth charges. The bathythermograph, a simple instrument lowered from a ship, measured temperature versus depth and became one of the war's most important secret weapons. The submarines that won the Pacific war owed their survival partly to oceanographers who had charted the invisible structure of the sea. Read more

Explore Collection

Cold War — Mapping for Strategic Advantage 1945 - 1990

SOSUS Connection

Sound Surveillance System — Undersea Listening Network

The surveying ships mapped more than the ocean floor — they mapped the acoustic environment that made SOSUS possible. The Sound Surveillance System was a network of hydrophone arrays anchored to the seafloor across the Atlantic and Pacific, designed to detect Soviet submarines by their noise signatures. Building SOSUS required detailed knowledge of ocean bottom topology, water temperature profiles, and the deep sound channel — a layer of water where sound waves travel enormous distances with minimal loss. Navy survey ships provided this data through years of classified oceanographic missions. Every chart of ocean depth and temperature was a building block in the undersea surveillance network that helped win the Cold War. Read more

Explore Collection

Modern Era — Pathfinder-class 1994 - Present

USNS Pathfinder

T-AGS-60 — Lead Ship, Pathfinder-class

Lead ship of the Navy's current oceanographic survey class, Pathfinder carries multibeam sonar that can map the ocean floor in swaths a mile wide with inch-level precision. Operated by civilian mariners under the Military Sealift Command, Pathfinder and her sisters conduct hydrographic surveys that produce the charts submarines use to navigate, the acoustic profiles that sonar operators use to hunt, and the bathymetric data that missile designers use to program cruise missiles. The name honors the Navy's surveying tradition — finding the path through waters no one has charted. Every safe transit through a newly surveyed strait, every submarine that navigates a seamount-studded passage without collision, owes something to Pathfinder. Read more

Explore Collection

T-AGS-62 — Pathfinder-class

Named for Nathaniel Bowditch, whose 1802 American Practical Navigator remains the foundational text of maritime navigation. Bowditch has operated extensively in the Western Pacific and South China Sea, conducting surveys that have occasionally drawn attention from the Chinese military. In 2016, a Chinese naval vessel seized one of Bowditch's underwater drones in international waters — a stark reminder that oceanographic data remains strategically valuable enough to fight over. Mapping the ocean floor in contested waters is not academic work. It is intelligence collection by another name, and the nations that contest those waters know it. Read more

Explore Collection

T-AGS-63 — Pathfinder-class

Named for Matthew Henson, the African American explorer who accompanied Robert Peary to the North Pole in 1909. Henson conducts oceanographic surveys worldwide, collecting the bathymetric, hydrographic, and environmental data that underpins everything from submarine navigation to amphibious landing planning. The ocean floor is not flat and featureless — it is a landscape of mountains, canyons, ridges, and plains that affects every aspect of naval operations. Henson maps that landscape with precision that Maury could not have imagined, using sonar systems that paint the bottom in three-dimensional detail. Read more

Explore Collection

USNS Bruce C. Heezen

T-AGS-64 — Pathfinder-class

Named for Bruce C. Heezen, the geologist and oceanographer who co-created the first comprehensive map of the entire ocean floor. Heezen's work in the 1950s and 1960s revealed the Mid-Atlantic Ridge and helped confirm the theory of plate tectonics. The ship that bears his name continues the tradition of revealing what lies beneath — conducting multibeam sonar surveys that produce three-dimensional maps of the seafloor with resolution that improves with every technological generation. The ocean covers seventy percent of the earth's surface, and most of its floor remains less well-mapped than the surface of Mars. Read more

Explore Collection

USNS Mary Sears

T-AGS-65 — Pathfinder-class

Named for Mary Sears, a marine biologist who joined the Navy WAVES in 1943 and became the first head of the Oceanographic Unit at the Hydrographic Office. Sears applied her scientific expertise to the war effort, producing ocean current charts and bathythermograph analyses that helped submarines hide and helped destroyers hunt. After the war, she continued as a leading oceanographer and helped establish the field as essential to naval operations. The ship named for her carries the most advanced survey equipment in the fleet — a fitting tribute to a woman who proved that understanding the ocean was as important as sailing on it. Read more

Explore Collection

T-AGS-66 — Pathfinder-class

Father of Ocean.

Named for Matthew Fontaine Maury — the circle complete. The man who first charted the oceans from ships' logs now has a modern survey vessel bearing his name, equipped with technology that would seem like sorcery to the nineteenth-century Navy lieutenant. Multibeam sonar arrays that map miles of seafloor in a single pass, satellite navigation accurate to inches, and computing power that can process and render three-dimensional bottom charts in real time. Maury represents the latest generation of the Navy's commitment to knowing the ocean — because the nation that understands the sea controls it, and the nation that controls the sea remains free. Read more

Explore Collection

6

Pathfinder-class

70%

Earth Under Water

T-AGS

Survey Mission

1842

Maury's First Charts