Imagine waking up, opening your front door…
…and stepping directly into the sea.
No boat.
No beach.
Just the endless blue of the Mediterranean.
It may sound like science fiction, but in the early 1960s Jacques Cousteau set out to answer a question that had fascinated explorers for decades:
Could humans actually live underwater?
The answer became one of the most ambitious diving experiments ever attempted.
Its name was Conshelf.
Quick Answer
What was Project Conshelf?
Project Conshelf was a series of underwater habitat experiments led by Jacques Cousteau between 1962 and 1965. The goal was to prove that divers could live and work underwater for extended periods using the principles of saturation diving.
The experiments became some of the most influential projects in the history of underwater exploration.
Before Conshelf
In the early 1960s, scuba diving was still in its infancy.
Divers could explore the underwater world, but only for relatively short periods before they had to return to the surface.
Cousteau believed there was another way.
Instead of sending divers down for brief visits, why not move their home to the seabed?
If they could live underwater for days or even weeks, they could spend far more time exploring, conducting research and carrying out underwater work.
It was an idea far ahead of its time.
Jacques Cousteau inspecting the water surrounding the Conshelf II © Robert B. Goodman—National Geographic
The Birth of an Underwater Home
In 1962, off the coast of Marseille, France, Cousteau launched the first underwater habitat.
Known today as Conshelf I, it was little more than a submerged steel cylinder placed about 10 metres below the surface.
Inside, two divers—Albert Falco and Claude Wesly—would spend an entire week living beneath the sea.
For the first time, humans didn’t simply visit the underwater world.
They lived there.
Did You Know?
Albert Falco, one of the two aquanauts of Conshelf I, later became Captain Jacques Cousteau’s chief diver and remained one of the most important members of the Calypso crew for decades.
Life Below the Surface
Living underwater wasn’t just about sleeping in a submerged capsule.
The aquanauts followed a daily routine much like astronauts aboard a space station.
Their days included:
- Scientific observations
- Underwater maintenance
- Marine biology research
- Equipment testing
- Photography and filming
- Medical monitoring
Everything they did helped scientists better understand how the human body responds to extended periods underwater.
Unlike ordinary dives, they didn’t need to decompress after every excursion.
Because they remained at the same pressure, they could leave the habitat, work outside for hours and return home repeatedly.
It was a completely new way of thinking about diving.
Conshelf II: An Underwater Village
The success of Conshelf I proved that humans could survive underwater for extended periods.
But Cousteau wanted to go much further.
In 1963, he launched Conshelf II in the Red Sea near Sha’ab Rumi Reef, Sudan.
This time, the project wasn’t just an underwater shelter.
It was an underwater village.
The Starfish house – Conshelf II © Robert B. Goodman—National Geographic
The main habitat, known as the Starfish House, was installed at a depth of around 10 metres and became home to five aquanauts for an entire month.
Nearby, a smaller, deeper habitat called the Deep Cabin was placed at approximately 30 metres, where two divers lived for a week under saturation conditions.
For the first time in history, people weren’t simply staying underwater—they were living and working at different depths as part of the same underwater community.
Living Like Aquanauts
Life inside Conshelf II followed a structured daily routine.
Each morning, the divers left the habitat to conduct scientific observations, test equipment, film marine life and carry out underwater engineering tasks.
At the end of the day, they returned to their underwater home to eat, rest and prepare for the next day’s work.
The habitat included:
- Sleeping quarters
- A small kitchen
- Scientific work areas
- Air and communication systems
- Windows overlooking the reef
Although conditions were simple by today’s standards, they were remarkably comfortable for the time.
For many divers, Conshelf II remains one of the most iconic underwater habitats ever built.
Did You Know?
The underwater village featured a small garage for Cousteau’s experimental diving saucer, allowing the team to launch underwater vehicles directly from the habitat.
Conshelf III: Going Deeper
Cousteau’s final experiment pushed the limits even further.
In 1965, Conshelf III was deployed off Cap Ferrat, France, at a depth of around 100 metres.
Six aquanauts spent more than three weeks living under saturation conditions while carrying out industrial and scientific work.
At the time, it was one of the deepest and most ambitious underwater living experiments ever attempted.
It demonstrated that saturation diving could make prolonged work at great depths both practical and efficient.
Many of the principles tested during Conshelf III would later be adopted by the offshore oil and gas industry.
The Birth of Saturation Diving
One of Conshelf’s greatest contributions wasn’t the habitat itself.
It was proving the concept of saturation diving.
Normally, every dive requires decompression before returning to the surface.
However, after spending enough time at a constant pressure, the body’s tissues become fully saturated with inert gas.
From that point on, staying underwater longer doesn’t significantly increase decompression time.
Instead of decompressing after every dive, saturation divers remain under pressure for days or even weeks and complete a single decompression at the very end of the mission.
This approach revolutionized commercial diving and is still used today in offshore construction, underwater engineering and scientific research.
Why Don’t We Live Underwater Today?
Given the success of Conshelf, it’s natural to wonder why underwater villages never became common.
The answer is surprisingly simple.
Living underwater is possible.
It’s just rarely practical.
Maintaining underwater habitats is expensive, technically complex and logistically demanding.
At the same time, advances in scuba equipment, remotely operated vehicles (ROVs), autonomous underwater vehicles (AUVs) and modern diving systems made permanent underwater habitats far less necessary.
The dream of underwater cities never disappeared—it was simply overtaken by more efficient technology.
The Legacy of Conshelf
Although the habitats themselves are long gone, the impact of Project Conshelf can still be seen today.
Its experiments helped shape:
- Modern saturation diving
- Commercial offshore diving
- Underwater habitat design
- Scientific diving
- Underwater filmmaking
- Long-duration human life-support systems
Perhaps even more importantly, Conshelf changed the way people imagined the ocean.
For a brief moment in history, it seemed entirely possible that the future of humanity might lie beneath the waves.
Final Thoughts
Project Conshelf was never just about living underwater.
It was about challenging the limits of what humans believed was possible.
While the world watched rockets climb toward the Moon, Jacques Cousteau looked in the opposite direction.
He believed that Earth’s greatest frontier wasn’t above us—it was below.
Although underwater cities never became reality, the lessons learned from Conshelf continue to influence commercial diving, marine science and underwater exploration more than sixty years later.
For divers, Conshelf remains one of the boldest experiments ever attempted—and a reminder that exploration isn’t only about discovering new places, but also about daring to imagine a different future.
The Cousteau Legacy
This article is part of The Cousteau Legacy, an ongoing Scubadiver series exploring the people, inventions and expeditions that transformed underwater exploration.
Jacques Cousteau: The Man Who Made the Ocean Visible
The Invention of the Aqualung: How Diving Became Truly Free
Calypso: The Ship That Changed Underwater Exploration
Conshelf: When Humans Tried Living Underwater
