Billionaire Facebook founder Mark Zuckerberg building enormous secretive underground bunker

The tech billionaire is in the process of building a luxury estate, rumoured to be costing him a cool US$260 million ($400 million), but included in the plans is a secretive underground bunker that’s twice as big as an average Australian home.

Reports about the project sparked concern in certain corners of the internet and saw a flood of inquiries directed at companies that construct sub-terrain shelters.

Mr Zuckerberg, executive chairman and CEO of Meta, which owns Facebook, Instagram and WhatsApp, hasn’t commented on the bunker revelations and anyone working on his property is bound by a strict gag order.

But it appears he has been quietly planning his fortified retreat for at least a decade.

Zuck’s shopping spree

It was Christmas in 2016 when Zuckerberg took to his social media platform to share happy snaps of his family enjoying the Hawaiian island of Kauai.

Home to about 73,000 locals, the pristine piece of paradise – known as ‘The Garden Isle’ – has served as the setting of major Hollywood productions, including Pirates of the Caribbean and Jurassic Park.

Most residents are descendants of Native Hawaiians, as well as Chinese, Puerto Rican and Filipino migrants who came to work on sugar plantations in the late 19th Century.

It’s also beloved by tourists from around the world, and more recently by the rich and famous.

“A few years ago, Priscilla and I visited Kauai and fell in love with the community and the cloudy green mountains,” Mr Zuckerberg wrote in 2016.

“We kept coming back with family and friends, and eventually decided to plant roots and join the community ourselves.

“We bought land and we’re dedicated to preserving its natural beauty. It’s filled with wildlife like pigs, turtles, rare birds and seals, and local farmers use it to grow fruits and spices. I love taking Max to explore and see all the animals.”

Records show he’d embarked on a frenzied shopping spree beginning in 2014.

A few days after his Christmas post, hundreds of Hawaiians who held a possible interest in small parcels of land within Zuckerberg’s estate were served with lawsuits by the billionaire.

Such is Hawaii’s colonial past that much of the land has a complex history of ownership, including a concept known as ‘kuleana’.

Hawaiian law allows the transfer of ancestral land to descendants without formal deeds, meaning a large number of people could hold shares in portions of land within Mr Zuckerberg’s compound.

His lawsuits offered those descendants a choice – either sell up or be legally forced to put the land up for public auction.

There was a fair amount of discontent among locals, but Makaala Kaaumoana, executive director of an environmental group in Hanalei on Kauai, thought the lawsuits were “a good thing”.

“It is always a sad thing when families lose their land, for any reason, but at least this way they are compensated,” Ms Kaaumoana told The Guardian.

An enormous compound

Since then, Zuckerberg has seized a total of 5.5 million square metres of land and surrounded it with a 2m high wall, with guards positioned along the perimeter and a security force conducting patrols on quad bikes.

To put the mammoth estate into perspective, that’s 1359 acres or 550 hectares of dirt – about 80 per cent of the size of Sydney’s CBD.

An investigation by tech magazine Wired uncovered details about what Zuckerberg, worth an estimated US$176 billion (AU$269 billion) has planned for his island estate.

“[The] compound consists of more than a dozen buildings with at least 30 bedrooms and 30 bathrooms in total,” the report revealed, sighting planning documents obtained by the outlet.

“It is centred around two mansions with a total floor area comparable to a professional football field [5295 square metres] which contain multiple elevators, offices, conference rooms, and an industrial-sized kitchen.

“In a nearby wooded area, a web of 11 disk-shaped tree houses are planned, which will be connected by intricate rope bridges, allowing visitors to cross from one building to the next while staying among the treetops.

“A building on the other side of the main mansions will include a full-size gym, pools, sauna, hot tub, cold plunge, and tennis court. The property is dotted with other guesthouses and operations buildings.”

But the most eyebrow-raising feature is away from view.

“The plans show that the two central mansions will be joined by a tunnel that branches off into a 5,000 square foot [464 square metres] underground shelter, featuring living space, a mechanical room, and an escape hatch that can be accessed via a ladder.”

The incredible size of the bunker, which has a blast-proof door, is double that of the average Australian home.

It will be entirely self-sustainable, producing its own food and water.

When complete, Zuckerberg’s Hawaiian estate will rank as one of the most expensive private properties in the world.

Few other details are known about the bunker.

Everyone who enters the property must sign a strict nondisclosure agreement, according to reports, and workers are sworn to secrecy.

Various media reports make mention of labourers being sacked after sharing selfies from the property on social media – posts that were quickly detected by Zuckerberg’s representatives.

“It’s fight club,” a former contractor told Wired. “We don’t talk about fight club.”

What does Zuck know?

When news emerged of Mr Zuckerberg’s bunker construction, Ron Hubbard, boss of Atlas Survival Shelters, said “it got really busy”.

“[It] caused a buying frenzy [and] the phone hasn’t stopped ringing [like] World War III is coming,” Mr Hubbard told The Hollywood Reporter.

One such bunker sold was a US$7.5 million (AU$11.5 million) underground compound in Oklahoma, he said.

Robert Vicino, founder of another bunker design and construction company called Del Mar, was also inundated with interest from interested buyers.

“Now that Zuckerberg has let the cat out of the bag, that’s got other people who share his status or are near his status starting to think, ‘Oh God, if he’s doing that, maybe he knows something that I don’t, maybe I should seek this out myself,” Mr Vicino told The Hollywood Reporter.

“But it’s no secret that the one-percenters and top-ranking government officials have been in on this bunker idea for a long-a** time. The pandemic was a huge driver of interest in sales; then all the global concerns and issues at home are another boost.”

A group on Facebook for Australian wannabe bunker-builders and “doomsday preppers” is filled with posts seeking advice about underground shelters.

There are queries about the fallout radius of a nuclear bomb dropped on Sydney or Melbourne, air and water filtration systems, suitable locations and more.

Although, there doesn’t seem to be many, if any local builders who advertise their services specifically for bunkers.

An operation specialising in underground shelters was active a few years back but appears to have been shuttered.

Atlas Survival Shelters claims it’s “coming soon” to Australia.

Mr Zuckerberg’s bunker certainly prompts a lot of theories about his motivation for the high-priced project, as well as plenty of conspiracies.

But in analysis written for The Conversation by Katherine Guinness, Grant Bollmer and Tom Doig for The Conversation, a far simpler logic is offered.

“Mark Zuckerberg’s net worth in 2024 is an almost unfathomable AU$260 billion,” they wrote.

“A $400 million Hawaiian fortress, extravagant as it might be, represents less than 0.2 per cent of his total wealth. As a percentage, this is comparable to a household with a net worth of $1 million (the average net worth in Australia) spending just $1,540.”

Those in the “billionaire bunker club” therefore don’t need to believe in the likelihood of some kind of apocalypse or societal collapse in a “committed or meaningful sense”.

“Instead, since they have far more money than they know what to do with, they may as well use a small fraction of it to build underground fortresses.

“Bill Gates, for example, owns at least eight properties in the US alone and, according to The Hollywood Reporter, ‘is rumoured to have underground security areas under every one of his homes’.

“For billionaires, putting money into such projects doesn’t mean they’re crazy, or paranoid, or in possession of some special secret knowledge about the future. It simply means they’ve amassed such colossal surpluses of wealth, they may as well use it for something.”

Bunkers are a booming business

So strong is the apparent demand for bunkers from the elite that a Swiss builder of shelters enlisted a leading French architect to design its range.

Marc Prigent, who trained at the École Boulle in Paris and runs his own practice, crafted the L’Héritage shelter for the company Oppidum.

Mr Prigent describes L’Héritage as “something entirely beyond any brief we have received for a secure space”.

“It’s designed, ideated and created without compromise to be worthy of our clients and the objects they seek to enjoy, preserve and protect,” he said.

Boasting five bedrooms and seven bathrooms, the sprawling bunker is packed full of luxurious touches, from its 5m high ceilings to a swimming pool, cinema, gym and even a mini art gallery.

“It’s hard to believe you’re deep under the ground, surrounded by thick layers of reinforced concrete – especially when you catch the scent of fresh flowers from the inner garden,” Oppidum said in its promotional material.

It’s also functional – gas tight, protected from blasts, including chemical, biological, radiological and nuclear weapons, and seismic resistant.

Some in the market for bunkers want the very highest level of protection, Strategically Armored and Fortified Environments president Al Corbi said.

Mr Corbi told The Hollywood Reporter that one customer – an unnamed business “mogul” – was desperately to ensure his family was protected, from anyone and anything.

“We wound up literally building a 30-foot-deep [9.1m] lake [around the compound] skimmed with a lighter-than-water flammable liquid that can transform into a ring of fire,” he said.

In other words, a moat of fire.

Mysterious Aussie bunker found

A few years back, an urban explorer who calls himself Jims Urbex stumbled across something incredible in an abandoned house in Adelaide.

While snooping around the remains of the dwelling, he noticed a pile of “scuffed carpet” and pulled it back to reveal a trap door.

Deep below was a bunker unlike anything he’d seen.

“This was no small one room air-raid shelter,” he wrote on his blog. “It was a fully decked out nuclear bunker that could sustain life underground for the foreseeable future (once society had crumbled, that is).

“The underground structure is the size of a small house, with a living room, kitchen, two bathrooms, and a bedroom.

“All the features that can aid in survival from a nuclear holocaust have been installed, such as multiple water tanks to hold purified water, an air filtration and purification system and multiple eight-inch thick blast doors.

“The blast doors were imported from overseas and made from solid metal. Now, I’m not the most athletic guy (with my weak office worker build), but when I tried to move these doors, it was quite a struggle. I could definitely see how they could keep out a hoard of bloodthirsty zombies.”