Burning Man on boats? Depending on whom you ask, this floating festival is a weeklong art party, a spiritual retreat from earthbound society, a social experiment in self-governance or all of the above.

Burning Man on boats? Depending on whom you ask, this floating festival is a weeklong art party, a spiritual retreat from earthbound society, a social experiment in self-governance or all of the above.

I’d just finished chopping up a watermelon with a dull hatchet on the wing of a floating platform called Siren Island when a party boat named The Entanglement motored over to offload a group of half-naked passengers.

Guests of Siren Island, a two-tiered wooden isle affixed with four spindly maple tree branches, were relaxing in the late-afternoon sun on the calm waters of the Sacramento-San Joaquin River Delta. They took turns plunging their hands into a steel basin of black lagoon mud then spreading it on one another’s skin — limbs, torsos and faces. The dozen or so passengers aboard The Entanglement had spotted the action from across the channel and were eager to indulge themselves.

“Permission to come aboard?” one hollered.

It was about 5 p.m. on a cloudless day at the height of summer — one of the last days of the annual weeklong floating festival known as Ephemerisle. The event, which just concluded its tenth year, draws a menagerie of watercraft and makeshift rafts to a remote corner of the delta for what is, depending on whom you ask, a weeklong art party, a spiritual retreat from earthbound society, a social experiment in self-governance or all of the above.

One longtime Ephemerisle-goer, Adam Katz, described it in an email: “The gathering is all of the inconvenience of Burning Man, plus the risk of drowning.”

At the center of Ephemerisle (pronounced eh-FEM-er-ile) was a one-of-a-kind craft, planned on land then assembled on the water and housing dozens of grungy delta campers. It was the multilevel island called Elysium, a compendium of barges, docks, platforms and pontoons all anchored and lashed together into a 3,000-square-foot Frankenmarvel of aquatic engineering. Among its amenities were an outdoor kitchen with gas grills and running water, a living room area replete with fireplace and antler mount, sleeping platforms loaded with camping tents and, to one side in a neat row, four orange portable toilets.

Off one end of Elysium, across a 20-yard floating plywood track, was a massive black tugboat covered in camping tents, the sides of its hull draped with tractor-size rubber tires. Another short dock led to a row of boats tethered in a solid floating block. There were smaller, independent islands of various forms with fun names like the Washed Up Yacht Club, DIYsland and Siren. But Elysium was the event hub, the sun around which the Ephemerisle solar system orbited.

There is no central leadership at Ephemerisle, no entry fee or sign-up sheet, and no admission tickets.

“There’s this roll-up-your-sleeves, we’re-just-gonna-build-it attitude that shines through here,” said Tom W. Bell, a law professor at Chapman University in Orange County and author who attended Ephemerisle the past two years. “It’s a very Silicon Valley ethos: ‘We’re just gonna do this.’ It’s everywhere here.”

The people who put together the islands aren’t just building a temporary respite. Many Ephemerisle participants view the event as an evolving experiment in competitive governments that could serve as proof of concept for a future in which human civilization migrates into the ocean. To them, each gathering represents an opportunity to inch toward a new vision of society.

Early on, I was informed that the founding principles of Ephemerisle were long lost, and the only surviving rule from the event’s first years is the most important: “No Dying.”

The area of the delta where the event takes place is overseen by the U.S. Coast Guard and San Joaquin County Sheriff’s Office and patrolled by local police boats. For several years — including this year — authorities have been called to respond to medical emergencies (in my reporting, I didn’t hear about any deaths at the event), but by and large, the floating colony has maintained a strong measure of self-reliance, a trait hardcoded into the event’s DNA.

Ephemerisle was founded in 2009, the brainchild of an ex-Google engineer named Patri Friedman (grandson of the late Nobel Prize-winning economist Milton Friedman), as a small-scale trial run of a concept called seasteading. A year earlier, with funding from tech mogul Peter Thiel, Friedman had founded the Seasteading Institute, an advocacy and research group that consults with governments around the world on creating new jurisdictions.

Imagine a future of floating man-made island-states, each independently governed and economically self-sustained. A person could select from a range of options on where to pledge citizenship, based on their taste for that colony’s philosophy and lifestyle. That was the genesis of Ephemerisle.

“The original intention was: Hey, we want to make new countries on the ocean,” Friedman said. “That sounds really hard. What if we can find an incremental path? What if we start a festival on the ocean where people get together for a week and live under different systems?”

But launching full-fledged atolls on the rollicking Pacific would have demanded a level of engineering savvy and, in Ephemerisle parlance, “saltiness” that participants just didn’t have. So Friedman and a large group of friends settled on an out-of-the-way estuary a short drive from San Francisco where currents are chill, access is easy and boat traffic is minimal. Then they started building.

Seren JV Elston (top) and two friends aboard Siren Island at Ephemerisle in the Sacramento-San Joaquin River Delta. Seren JV Elston (top) and two friends aboard Siren Island at Ephemerisle in the Sacramento-San Joaquin River Delta. Photo: Carter Grimes Photo: Carter Grimes Image 1 of / 5 Caption Close Ephemerisle festival is Burning Man on boats in the Sacramento River Delta 1 / 5 Back to Gallery

The learning curve was steep that first year, Friedman said. He built a small wooden “pyramid” out of hardware-store materials, buoyed it with empty water jugs, stuck a motor on one side, strapped on a life jacket and set sail. But there was so much drag that the thing barely moved. After a while puttering along, he got bored, tried climbing one of the pyramid pillars and flipped over.

“I swam to the shore,” Friedman said. “I had my cell phone in a waterproof bag and called for rescue and they brought me in.”

Other participants fared better, and Friedman spent the week on a houseboat. In a short video documentary of that first year, you can see glimmers of unique crafts and a community spirit taking shape. Still, the end result — a collection of houseboats and some rickety wood structures — was a far cry from the grandiose ideal of a floating libertarian Waterworld.

“I am not entirely certain I can see the throughline between this and the ultimate end seasteading goal of independent freeholds out in international waters,” Brian Doherty, an early Ephemerisle participant, said in the documentary. “Seasteading, to be viable moving forward, has to have all of the aspects of a human civilization. The most important aspect of which is it has to be productive, not merely consumptive.”

Friedman officially gave up on the event a year later to focus on the Seasteading Institute. But the seed had been planted, and Ephemerisle has carried on without Friedman at the helm. (He has attended for fun several times since then.)

The gathering has shape-shifted each year since, depending on who shows up and what creations they bring.

Dubbing the event “Burning Man on water” wouldn’t be quite fair, although there is crossover between the two communities, a similar bohemian aesthetic and a certain appeal among alternative thinkers and audacious engineers. It’s less a gathering of seasoned sailors (though there are some delta rats) than a weeklong DIY raft-up of free-spirited city dwellers in funky outfits. Self-expression and its accoutrements are rampant.

Toward the end of the festival in July, I spent a day exploring the gathering on a Jet Ski. It takes place at the tip of Mandeville Point, about 15 minutes (give or take) from Korth’s Pirates’ Lair Marina, south of Isleton. Unlike the setting at Burning Man, Ephemerisle is within easy reach of civilization. While launching my boat, I spotted festivalgoers loading up on water jugs and bags of ice at a local shop. More waited for a ferry pickup from a person at the event. A small group loaded a barge with art supplies and building materials, including a small maple tree in a wooden planter box. One woman in the group planned to install it in a buoy and set it free on the delta.

Bounding through the channels, the gathering wasn’t hard to spot. I throttled down to cut my wake and take in the scene.

On one motor yacht, people took turns diving off the high bulwark. A man in a small skiff cruised the channel on a gust of wind. Someone had fashioned an old RV shell into a small houseboat. On the black tugboat, a man in a Speedo played what sounded like a recorder while a shipmate on deck behind him fumbled around in a VR headset, arms outstretched. Sunbathers lazed about. Many people were napping in houseboats or below decks, avoiding the sun and recovering from the previous night’s party. A long black craft called Venom Sound Ship made endless loops through the fractured colony of boats, spouting dance music.

Several people I spoke to heard about the event through the Burning Man community. Some, like Tom W. Bell, are compelled by the seasteading element. Others, like Venom Sound Ship captain Scott Rizzo, regularly appear at maritime events around California. A few stumbled upon it and were intrigued enough to stick around.

Martha Esch, a tan woman moored on the shore of the channel in her cabin cruiser, first attended Ephemerisle three years ago after learning about the gathering while attending a nearby Fourth of July fireworks show. Several young people from the Bay Area I spoke to learned about Ephemerisle via Facebook.

One foursome on a houseboat had never heard of the event but happened upon it during their vacation in the delta and wound up hanging around for the spectacle.

“We have binoculars, so we’ve been keeping ourselves busy,” said Sandy Carter, calling across the water from the rear deck of the boat, where she and three friends were sipping cocktails and playing cards. Someone had motored over to them when they arrived and explained the gist of the gathering. “Most of us don’t know what Burning Man means … but we’ll go home and look it up on our phones,” Carter said.

About 50 yards away, a couple dove off the rear of a boat and began swimming across the channel to Elysium, where an ad hoc presentation forum was getting under way. A handful of people busied themselves preparing Siren Island to receive guests while an enormous freighter coasted across the channel just south of the gathering.

Overall, the attitude was live and let live. Some people had been living the life all week, others were new arrivals, just in time for the closing party. Boaters helped each other with building projects and resupplies and were generous with invitations to host visitors. Katz, the longtime festivalgoer, summed up the vibe to me in an email: “If they came for Ephemerisle, they’re part of Ephemerisle.”

The event in July would have felt fractured and unmoored if not for the gravitational pull of Elysium, the big island at the center of the gathering.

While most boats at the festival kept their captains and maybe a small handful of guests, Elysium was responsible for boarding and feeding dozens of campers for as long as a week. That kind of operation doesn’t come together without careful planning and, above all, rules. For that, the island represented the closest embodiment of the seasteading ideal upon which Ephemerisle was founded.

“To me, rules are to Ephemerisle what art is to Burning Man,” Friedman said. He called the process of forming cohesive group identities and drawing parameters around acceptable conduct and behavior Ephemerisle’s “artistic spirit.”

“All of those challenges — that’s the heart of the festival,” Friedman said. “Some people will get it and be enthusiastic, and some people will ignore it and party.”

Tom W. Bell is the former. His book, “Your Next Government?,” is an account of how “special jurisdictions” may come to replace nation states. He has consulted on seasteading proposals in French Polynesia and elsewhere. “I want to be involved in this experiment in governance,” Bell said. “I want to see how it happens in this highly decentralized, truly voluntary environment.”

He signed up to work as a “guide” on Elysium at night, during party time. The basic job description: patrol the island, hand out flashlights and whistles to guests who may need them, and make sure no one hurts themselves. “It’s risk mitigation,” he said.

Bell worked in tandem with a “greeter,” who walked new arrivals through initiation and presented them with documents to sign — which focus in part on the importance of “enthusiastic consent” among people on the island — and handed them a wrist band. “It’s really border control,” Bell said. “We have to protect our boundaries so no one comes and hurts the people we have there.”

(I couldn’t get a firmer read on the inner workings of Elysium because of one of the island’s core principles: “No Media.”)

Previously, the area where the greeter met new arrivals was called the “immigration station.” Some people “were questioned about consent in a way that felt like interrogation,” Katz wrote in an email. “It broadened the divide between islands and made some people feel very unwelcome.” Elysium later dropped the immigration station name. Arrivals this year were greeted at a “welcoming station.”

At one point during his stay this year, Bell encountered a greeter in what looked to be a heated exchange over the island’s documentation with a woman who’d just arrived. He sat down to help ease the tension, patting the greeter on the back. “I want them to see he has people on his side, and I say to him, ‘You’re doing right here. You’re protecting the people who are taking the huge risks to put this place together,’” Bell said. After that, the woman and her partner signed the paperwork.

“I don’t know if that helped. But I think that’s how governance works here,” Bell said. “It’s not about goose-stepping these people off the barge. Let’s do this in a gentle, sociable way."

“One of the things I love about this is it plays out, on a very small scale, the issues we deal with on a national scale,” Bell said. “Who does government perfectly? No one. If humans are involved, it’s going to be a mess.”

A stream of dance beats flowed over the warm delta channel as The Entanglement, loaded with passengers and outfitted with a makeshift DJ booth, made its way toward Siren Island.

Boaters are taught to dock by lining up their bow parallel to the docking platform, approaching slowly, then swinging in their stern. But The Entanglement approached the low bow of Siren Island head-on, landing with a hard thud and crunch of party-boat metal grating against the island’s redwood planks.

“Hey!” Serena JV Elston, Siren's creator, hollered at The Entanglement. She turned to me. “This is the s— I hate.”

In no time, the boatload of partiers had hopped onto the island’s flat nose, straining the ballast of the pontoons supporting Siren and causing the island to pitch and yaw. The island’s wings began taking on water, house music from The Entanglement playing over the commotion.

Elston, a woman with wild wavy brown hair and wearing a blue bathing suit, turned to the small crowd, instructing them to spread out and distribute their weight. The Entanglement shifted into reverse, ripping a plank off the island with a loud crack.

“OK, time for you to leave!” Elston yelled to the skipper, a blond man with headphones around his neck. “You don’t even have bumpers, dude!”

Many, if not most, Ephemerislers live full-time on land, so inter-vessel visitations can have a bumper-boats quality. Making human life happen on the water is a fundamental challenge of the event, and without proper instruction, Ephemerisle participants muddle through on messy experience.

In hosting visitors to Siren Island nonstop, Elston was keenly aware of that knowledge gap. She pointed to a cleat at my feet tangled in a thin silver chain that a visitor had attached with a small combination lock to secure his kayak. “This is exactly what I’m talking about,” Elston said. “What the f— is that?”

A man with curly hair named Adam replied: “It’s people bringing their terrestrial s— with them.”

Whether Ephemerisle is growing or shrinking is tough to say. There are no ticket sales or census numbers, and while longtimers say there was a big drop-off several years ago when the local houseboat rental industry folded, numbers appear to have bounced back a bit. Best guess? It’s roughly stable, with at least a few hundred participants each year.

In many ways, it has come to inhabit the purpose assigned by its creator: a hodgepodge of flotsam and philosophy that amasses at the same time and place each summer, with certain communities gaining strength and stability while neglected ones atrophy. It draws people who are curious and audacious enough to give themselves over to a communal experience with no central leadership. Your safety net is your neighbors.

Yes, there are glow sticks, tents, onesies, didjeridoos, psychedelics, dubstep, mohawks, fishnets, tattoo stickers, cuddle puddles, pirate flags, dreadlocks, gurus, Buddhists, DJs, Buddhist-DJs and armchair libertarians galore. Why wouldn’t there be?

There’s also live improvisational music sets, collaborative art projects, ad hoc engineering solutions, presentation forums, deep conversations, communal sunset “howlings,” bonds forged and a constant swirl of innovative ideas and institutional wisdom.

Some people I interviewed think the spirit of Ephemerisle is dead or irrelevant, the core principles rendered moot, the excitement of venturing into unchartered waters neutralized. To others, it’s alive and intact, buzzing with activity and brimming with potential. But cultural phenomena are fluid and amorphous, and a person’s perspective on their potency and authenticity depends on the timing and circumstances of an individual’s point of entry. What’s clear is that the experience is special to everyone who goes — whether that’s to party or to dabble in low-level world-building.

In my short time there, I found that I was most happy when I was contributing. Hacking away at the watermelon under the warm sun on Siren Island, ferrying a friendly stranger over to Elysium, sharing information about the event with the people I encountered. Everyone had an opinion, everyone was trying to figure Ephemerisle out — what it was, what it is, and what it could one day become.

***

Early on my first day at Ephemerisle, before the snafu with The Entanglement, I jet-skied over to Siren Island to say hello to Elston. Reclining on the bow was a pale, naked woman with long wavy ginger hair and gray eyes — Botticelli’s Venus, I thought. My approach was too fast and before I could maneuver I’d set the nose of my boat on a collision course with one of Siren’s wings.

Thump.

A few strangers on the island shot dirty looks my way. Heat flashed into my cheeks and a pang of embarrassment wrenched my stomach. I was so clearly a newb, a kook, a landlubber — so obviously not salty — dead weight at an event that needs all the buoyancy it can get.

I stammered out a few quick apologies. At the bow, Venus seemed unfazed.

“Eh,” she shrugged. “You live, you learn.”

Gregory Thomas is Travel Editor at The Chronicle. Email: gthomas@sfchronicle.com. Twitter: @GregRThomas.