What happens when you put 2000 nerds on a boat?

You get the JoCo Cruise, and it's an annual gathering for those who love sci-fi, games with many-sided dice and the musician Jonathan Coulton.

It is the first concert of the JoCo Cruise 2019, and things are going so wrong. The musicians can't hear themselves sing. Instruments drop out at random. One of the performers, Jim Boggia, has lost his voice.

Jonathan Coulton, the singer-songwriter for whom the cruise is named, grouses that it is a "train wreck on a boat."

They carry on, trying to wrestle a show from the mess. Boggia starts playing When You Wish Upon a Star on his ukulele and raspily invites us all to sing along. The assembled hundreds join in a mass mumble, but one woman's voice stands out and confidently rises, clear and lovely. Paul Sabourin, another of the performers, hops off the stage and hands her a microphone. The performers complete the song to rousing cheers.

I spot the singer. She is wearing extravagantly long elf ears.

Now in its ninth year, the JoCo Cruise is a grand annual gathering of the nerd tribe. You may not have heard of Coulton, who left his job writing software in 2005 to explore a music career, but he has built a fervid online community of fans. He writes quirky, funny and often sneakily touching songs that play off geeky themes, including Re: Your Brains, about the guy who works in the office down the hall from you and who is a zombie now, and Skullcrusher Mountain, about a mad scientist trying to woo a woman his assistant, Scarface, has abducted. (Sample lyric: "I made this half-pony half-monkey monster to please you/But I get the feeling that you don't like it/What's with all the screaming?"). Coulton is also the in-house musician for the NPR game show Ask Me Another, and wrote the end credits song, Still Alive, for the best-selling video game Portal.

The JoCo Cruisers are here to hear music from him and the other performers, sure, but there's more: For lovers of science fiction and fantasy there are novelists giving talks and being generally smart and funny, there are stand-up comics, some journalists and even an astrophysicist giving a late-night lecture on when and how the universe could end. Most of the performers are what Felicia Day, the actor and writer, calls "situationally famous": not recognised on the street, but superstars at places like Comic-Con and on the internet. The cruise also caters to a broad range of fascinations, including board games with many-sided dice, tech, crafts, cosplay and a zillion fandoms.

At this point, some readers — maybe you, we're not judging — might be thinking that if they found themselves dropped into the middle of all this, they would be tempted to jump over the railing into the wine-dark sea, seeking the sweet release of death. But there are 2000 people here, having a blast. This year, JoCo sold out the entire Oosterdam, a Holland America Line ship. It departed in early March from Fort Lauderdale, Florida, for a week long trip with stops in Half-Moon Cay in the Bahamas, and Tortola, part of the British Virgin Islands, as well as San Juan, Puerto Rico.

The rise of the 'affinity cruise'

A nerd cruise might sound very specialised, but specialisation is a big part of cruise travel, said Michael Driscoll, editor-in-chief of Cruise Week, an industry publication. Affinity cruises, as they are called, are "a huge component" of the cruise business that is all but "indestructible to the business trends." Conservatives can head out to sea with The National Review, while liberals can set sail with The Nation; sites like Theme Cruise Finder have trips that cater to every conceivable interest. The JoCo cruise is often referred to as "nerd summer camp at sea," said Sabourin, half of the comedy-music team Paul and Storm and one of the four people who plans and runs each cruise. The common thread, he said, is "indoor-kid things."

It is a colourful crowd, literally. Many of the sea monkeys — the name is a play on a Coulton song, Code Monkey, about a lovesick software writer — stand out in the everyday world, with their flamboyantly dyed hair and extensive and intricate tattoos. There is a healthy contingent of LGBT folks, as well. As I boarded the Oosterdam, I felt a little like an outsider, with my graying, undyed hair and conspicuous lack of tattoos. But I soon realised that my fellow passengers were not significantly more eye-catching than are a fair number of my co-workers and also realised there were plenty of dull folks like me, including families with children, blending into the background.

"For people on the far sides of the bell curve, this is a once-a-year opportunity to be themselves — and it's heartwarming to watch," said Anye Shafer, a software architect from the Dallas area on her fourth cruise. "You can be — except, maybe a serial killer — anything you want to be, and people will take you at face value, and accept you for who you are."

Jenny Ross, a fifth-time sea monkey, said activities all over the ship during the week share one trait: enthusiasm. "I'm guaranteed that no matter what room I walk into, I will find people who are passionate, people who are knowledgeable, people who are excited to be doing whatever they are doing," she said. Ross and her husband, Chris, a software engineer with Microsoft, leave the children with their parents for a week while he plays board games and enjoys the music, and Jenny, who left the software world to raise the children, geeks out on puzzles and acts as an "ambassador" to first-timers, inevitably known as "new monkeys." She wore a pink sash that read "Ambassador," but it was not as eye-catching as her dark skirt, which was webbed with small lights, giving the impression of a starlit night. The couple also attached tiny hats to their hair with bobby pins; He, a red fez; she, a gold party hat.

They took a more typical cruise some years before, and "we were almost the only people under 50, and the onboard entertainment was not meant for us," Jenny Ross said, imitating the announcer: "Make sure to stick around for bingo — it's the height of stimulation!" She laughed. "I like this one better. I don't get weird looks for having a tiny hat on my head."

The cruise can be intensely social, with built-in conversation starters. Everyone's name tag has room to write down something to "ask me about ... " So as people pass in the buffet, topics wander by that include "Dungeons and Dragons," "CCL" (Citizens' Climate Lobby), "Anxiety and Depression," "Baking!" and "My Bone Spurs."

But the cruise goes very far to make introverts and the socially awkward comfortable, as well. At check in, everyone is offered two "Friendshipping" buttons that describe your attitude toward conversation: a big green YEAH for those who invite contact, and a red NAH for those who would rather not. The concept, which has precedents in the autism community, works beautifully for the merely shy. Sections of the ship are deemed quiet zones, and those who don't want to attend the crowded, raucous evening concerts can watch a simulcast in a darkened lounge or even on the television in their cabins. The result is a floating community of friends, even if they have never met. "You'll never find a group of nicer, more kind people," said Linda Shapley, a former managing editor of The Denver Post making the trip with her husband, Ed.

One longtime sea monkey, CeeCee Stein, found the community so accepting that several years ago she decided to use a cruise as her moment to transition from male to female. "I got on the plane as Christopher, and I got off the plane as Christina," she recalled. "It seemed like the group of people I would most want to lay my soul bare in front of," she said.

She added, "I call it my birthday."

It's a make-your-own-fun environment: Fully half of the 344 programs during the week were created by the passengers; their activities are called the "shadow cruise." The programming came to 605 hours of activities or 25.46 days' worth over the seven-day cruise. There is so much to do that on the first night, the organizers warn against overdoing things, laying out what they called the "5-3-1 rule": Make sure to get five hours of sleep a night, eat three meals, and "one shower or bath per day," a line that got a knowing laugh from the crowd.

On the second day, after getting sand between my toes on Half Moon Cay, I wandered over to JoustMania, one of the shadow cruise activities. Presented by a guy who goes by Loki and has a particularly fine lavender beard, JoustMania does not involve horses or lances. Players hold game controllers that look a little like microphones with a light-up top that are sensitive to motion. The idea is to jostle your opponents' controllers without letting your own be jostled. Get jostled and the color of the controller changes and a crashing sound occurs; you're out until the next round.

The game began. Music played; ragtime pieces mainly, that sped up and slowed down, which somehow affected the sensitivity of the controllers. The players warily stepped around each other, attempting slaps at arms while protecting their own controllers. It looked like a dance, or a form of martial arts practiced on a space station. A woman in a Doctor Who "Tardis" dress glided by like quicksilver on a plate. "She teaches yoga," a friend noted.

I was quickly taken out by a teenager. In my defence, I believe she may have been a trained assassin.

Making room for the 'nerd adjacent'

A few weeks before the trip, I spoke with John Scalzi, a best-selling author of science fiction and a JoCo regular. Along with his duties as a situationally famous writer, which involves leading writing workshops and doing readings of his work, he is a kind of avatar of goofy fun. Joyful and hammy, he belted out Cruella De Vil at the cruise's Disney singalong and also hosts an end-of-cruise dance party.

I asked him, "Am I nerd enough for this cruise?"

"Dude," he said laughing, "Yes. You are." That wasn't just about my own obvious demi-nerdiness, but also the fact that many people who are not nerdy in any way, like Scalzi's wife, Krissy, enjoy it. He refers to such people as "nerd adjacent." Besides, he noted, "the line between what has classically been nerdy and what is classically mainstream has begun to fluctuate and flow." Last year's biggest film? "Black Panther," based on a comic book. "The mainstream world and the nerd world are thoroughly intermixed now," he said.

Which brings us to Jonathan Coulton. When I first booked a cabin, I thought of him as the tent pole of the event, the reason for everything. It didn't take me long to realise he's more like its maypole: standing at the center, with an enormous and intricate dance going on around him.

Coulton and I sat together by the Lido level's open-air pool for a conversation. He said members of this community, which is active year round on Facebook, "feel a kind of ownership that transcends me and my music," adding, "If I said, 'There's no more JoCo Cruise!' I'm certain that a number of sea monkeys would take it upon themselves to do another cruise."

Still, his wry wit infuses everything. He loves that for each of the nine years, there has been a "Fancy Pants Parade" on board the ship, based on a throwaway song he wrote as an act of "desperation" to keep up a song-a-week project. Just a minute and a half long, the song tells of a competition over who has the fanciest pants. Somehow, it is poignant. And now, he noted, people promenade on the deck in fancy pants, or "fanciful interpretations of pants." There are trophies. "To have written this ridiculous song off this ridiculous idea and see it come to be a real thing in the world, it's a remarkable thing as an artist."

How this chaotic miracle comes together is the work of Coulton, Sabourin and Greg DiCostanzo, who is the "Storm" of Paul and Storm, and Drew Westphal, the chief operating officer of the partnership. Sabourin and I met to talk in the ship's casino, a place we knew would be quiet. In a lounge across the way, the JoCo planners set up more than 40 vintage video game consoles, which drew a crowd day and night. On the casino side, the dealers had nothing to do. "Everybody here actually understands probability," Sabourin joked.

These folks haven't always had an entire ship to themselves. The first cruise attracted about 350 Coulton fans. It's grown, year by year until three years ago they were able to book a ship. This year, the ship sold out. Next year's cruise, on an even bigger ship, is selling out fast. No cruise yet has lost money, Sabourin said.

To Sabourin, the cruise is not just a job — in fact, a multimillion-dollar-enterprise — and exhausting fun, but also a mission. The organizers seek a diverse cast of performers and passengers. The cruise also raised some US$80,000 for Puerto Rico after 2017's devastating Hurricane Maria.

"We're helping bring people joy, helping them learn new things and getting them out of their comfort zone," Sabourin said. "I want people to be better for having attended this event. Maybe that sounds lofty from someone who writes humorous music for a living, or incongruous for an event happening on a giant floating hotel. But I stand by it."

To the brink of disaster

The third night of the cruise started with an LGBT-friendly dance party on the open deck of the ship as it slipped out of the pier at Tortola. The mood was light, and the deejay, Riz Rollins, spun songs with his husband, Rob Green. Before his first cruise last year, he said, he'd expected a very white crowd, given the reputation of nerds, but was pleased to encounter a more diverse group. "I didn't know what a 'blerd' was until the cruise," he said, using the portmanteau term for black nerds. He marveled, too, at the degree to which the JoCo culture is participatory. "It's the first time I ever saw people dance — to karaoke."

The next night was supposed to be the biggest show of the trip, an outdoor concert in a San Juan park after a day wandering the city. The lineup included well-known performers like Aimee Mann and Jill Sobule, and the headliners were They Might Be Giants. (Mann, a Grammy-winning singer-songwriter who is anything but nerdy, said in an interview that "It's not really my crowd, but Jonathan encompasses a lot of different things under his umbrella.")

It rained: Off and on, at first, but after Coulton's performance, and just before They Might Be Giants were supposed to take the stage, it turned into a pounding downpour. Many people sheltered at the open-air bar, which at least had a roof. We were all drenched and cold, and it looked as if the concert had been rained out just before the biggest act. At another music festival, customers might grumble, or even riot. These people began singing.

"Don't stop believing," they belted. The bartenders, loving the happy crowd, handed out rum shots with anise liqueur, and then rum shots with cider, further fueling the ebullient mood.

A chant suddenly went up: "We're going back to the boat! We're going back to the boat!" The musicians had decided to move the equipment back to the Oosterdam to finish the concert there. A crowd that understands probability knew that this might not come off. Making it even less likely was a rule that guests have to be off a boat one hour before its scheduled departure. If they were not, the cruise line could be fined tens of thousands of dollars. The deadline was midnight. And it was already well after 10pm.

Shoes squelching and fingers pruny, we hustled back to the ship in the rain, and into a lengthy security line. Coulton and the Giants' John Linnell (the one who plays the accordion) rushed by to the right of the line, wet and bedraggled but determined. The crowd cheered them on.

Back on the ship and after a lightning-fast sound check, the doors to the ship's main performance hall opened. It was just after 11. The audience rushed in. Many had taken a moment to return to their cabins to towel off, and were wearing everything from Holland America Line bathrobes to bathing suits and footed pajamas. The band blazed through a 50-minute set, with crowd-pleasing hits like "Birdhouse in Your Soul" and "Dr. Worm." They hustled off the stage by 11:55, and were off the boat at precisely one minute before midnight.

As Linnell stepped off the ship, his hair still damp, he said, "It seemed impossible."

But somehow, it had worked. Once again, beauty had emerged from chaos, another train wreck on a boat — or off it, technically, and then back on it again — had been averted. With even more chaos, even more beauty, and joy.