Glomar Explorer
Philadelphia, Philadelphia County, Pennsylvania
Marker Inscription
In a covert CIA plan named the Jennifer Project, this ship was built at Sun Shipbuilding and Dry Dock Company, Chester, in the early 1970s and played a key role in US Cold War espionage. Its mission was to obtain intelligence by recovering a sunken Soviet submarine, three miles deep in the Pacific Ocean. Portions of the sub were raised by the ship's huge claw in the summer of 1974; six Soviet submariners were recovered and given a burial at sea.
Erected by Pennsylvania Historical and Museum Commission
The Story
At the height of the Cold War, the CIA hatched one of its boldest intelligence gambits: recovering a Soviet submarine from three miles down in the Pacific. The cover story was billionaire Howard Hughes mining the seabed for manganese, but the true purpose was espionage, and the Glomar Explorer—built at the Sun Shipbuilding yard in Chester—was the improbable machine to do it. In 1974 its giant claw lifted portions of the wreck, and the recovered Soviet sailors were given a burial at sea.
Why it matters
The mission gave rise to the famous 'we can neither confirm nor deny' response and stands as one of the most audacious feats of Cold War espionage and American marine engineering.
The story behind this marker
AI contextThe era
The early 1970s were the deep Cold War, a standoff fought less with open battle than with secrets. The United States and the Soviet Union matched each other missile for missile and submarine for submarine, and both sides poured extraordinary sums into learning what the other knew. Intelligence — especially about the enemy's nuclear-armed submarines — was worth almost any price and almost any risk.
That hunger for intelligence met, in this era, an American industrial confidence that believed almost any machine could be built if the need was great enough. The nation that had sent men to the Moon at the close of the 1960s was not inclined to think that three miles of seawater was an insurmountable obstacle.
Philadelphia sat within one of the country's great shipbuilding regions, and just downriver at Chester stood the Sun Shipbuilding and Dry Dock Company. It was exactly the kind of heavy-industry yard where an audacious idea could be turned into steel — and in the early 1970s, one of the strangest projects of the entire Cold War took shape there.
People & events
The ship was the Glomar Explorer, and the covert CIA plan that called it into being was known as the Jennifer Project. Built at the Sun yard in Chester in the early 1970s, the vessel was designed for a mission almost beyond belief: to reach a sunken Soviet submarine resting roughly three miles down on the floor of the Pacific Ocean, and to raise it for the secrets it held.
To do that, the ship carried an enormous claw meant to descend into the crushing dark, grip the wreck, and lift. In the summer of 1974 that machinery went to work, and portions of the submarine were brought up from the abyss. It was a feat of marine engineering at the absolute edge of what the age could attempt.
The mission also had a solemn human dimension. Among the recovered portions of the sub were the remains of six Soviet submariners. They were given a burial at sea — a quiet act of respect rendered to fallen sailors of the very navy the operation was built to spy upon.
Its place in the American story
Project Jennifer has become one of the legendary episodes of Cold War espionage precisely because it combined deep secrecy with staggering technical nerve. It stands as a monument to how far the superpowers were willing to go, and how much they were willing to spend, to pry loose the other side's military secrets beneath the notice of the public.
It is remembered, too, for what it taught about official silence. An operation this sensitive could be neither admitted nor denied, and the careful refusal to confirm or deny such things became a lasting fixture of how governments answer questions they cannot answer. The Glomar Explorer's shadow reaches into the very language of secrecy.
And it is a distinctly American engineering story. The idea that you could purpose-build a ship to recover a wreck from three miles down — and then actually launch it from a yard on the Delaware River — captures a moment when American industry believed no technical problem was truly out of reach.
If you visit
This is a landmark of story more than of spectacle, so come prepared to use your imagination. Standing near the Philadelphia waterfront, look out at the river and the broad industrial reaches downstream toward Chester, and picture a yard large enough and bold enough to assemble a ship for a mission to the bottom of the Pacific.
Let the ordinary working river do the work. The Delaware has built vessels for generations, and the power of this tale is that something so secret and so strange grew out of such a practical, everyday place. The contrast between the plain industrial setting and the almost unbelievable purpose is the whole thrill of it.
If you're piecing together a road trip through the region's Cold War and industrial history, this marker makes a natural anchor. Read it slowly, then watch the water for a while, and remember the six sailors given back to the sea far from home — the human heart of an operation that was otherwise all secrecy and steel.
Written by AI to add context, grounded in the marker’s inscription and the historical record. The inscription above is the original, unaltered text.
Plan your visit
NearbyMake a day of it — museums, food, and places to stay near this marker.
Museums & culture
- Merchants' Exchange Building0.3 mi away · 143 South 3rd Street, Philadelphia, PA
- Independence Living History Center0.3 mi away
- Museum of the American Revolution0.3 mi away · 101 South 3rd Street, Philadelphia, PA
- Powel House0.4 mi away · 244 South 3rd Street
- Larry Becker Contemporary Art0.4 mi away · 43 North 2nd Street, Philadelphia, PA
- Science History Institute0.4 mi away · 315 Chestnut Street, Philadelphia, PA
Attractions
- USS Olympia0.2 mi away · South Christopher Columbus Boulevard, Philadelphia, PA
- USS Becuna0.2 mi away · South Christopher Columbus Boulevard, Philadelphia, PA
- City Tavern0.2 mi away · 138 South 2nd Street
- First Bank of the United States0.4 mi away · 120 South 3rd Street, Philadelphia, PA
- Carpenters' Hall0.4 mi away · 320 Chestnut Street, Philadelphia, PA
- Elfreth's Alley0.5 mi away
Food & drink
- Olivier Cafe0.4 mi away · 50 South 3rd Street, Philadelphia, PA
- FRIEDA0.4 mi away · 320 Walnut Street, Philadelphia, PA
- National Mechanics0.4 mi away · 22 South 3rd Street, Philadelphia
- Menagerie Coffee0.4 mi away · 18 South 3rd Street, Philadelphia, PA
- PrimoHoagies0.4 mi away · 304 Market Street, Philadelphia, PA
- Buddakan0.4 mi away · 325 Chestnut Street, Philadelphia, PA
Places to stay
- Hilton Philadelphia at Penn's Landingnearby · 201 South Christopher Columbus Boulevard, Philadelphia, PA
- Philadelphia Marriott Old City0.2 mi away · 1 Dock Street, Philadelphia, PA
- Thomas Bond House0.2 mi away · 129 South 2nd Street, Philadelphia
- Penn's View Hotel0.3 mi away · 14 North Front Street, Philadelphia
- Apple Hostels0.3 mi away · 33 Bank Street, Philadelphia, PA
- Apple Hostels Philadelphia0.3 mi away · 32 South Bank Street, Philadelphia, PA
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Related events
- · Project Azorian / Jennifer Project
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