Scenes from the Bruise Cruise aboard the Carnival Imagination

Spitting distance from several massive, gleaming-white cruise ships docked in Nassau, Bahamas, a couple hundred people squeeze inside Señor Frog's Restaurant and Bar, a tourist trap kitted out with neon signs reading, "Rehab Is for Quitters" and "Divorce: Future Tense of Marriage" — not to mention barstools that look like women's butts in bikini bottoms. It's small — only slightly larger than an open-air, seaside Burger King. But space is not the issue. Two distinct groups pack the place, and they're not exactly enjoying each other's company.

One half of the crowd is aging, sunburned, and dressed in crisp, clean outfits from the mall. They arrived expecting a typical spring break experience. The other half of the crowd came for something very different. Sporting neon sunglasses, ironic mustaches, and eye patches, they're here to watch garage rockers such as the Black Lips, Strange Boys, and the Vivian Girls tear the joint to shreds.

This entirely out-of-place rocker contingent comes courtesy of the inaugural Bruise Cruise, an attempt by Carnival Cruise Lines to get cool kids on one of its boats. For the last weekend in February, Carnival reserved 400 spots on its 2,000-person Imagination ship for "bruisers," who paid $615 to catch nine indie bands playing rooms normally dedicated to lounge acts.

Inside Señor Frog's, meanwhile, the first few bands further alienate the aging and sunburned. There's really only one moment of mutual listening enjoyment: the Vivian Girls' distortion-heavy cover of Céline Dion's "My Heart Will Go On." And as midnight looms, the Black Lips — known for beer-spraying, crap-taking, and chicken-teasing onstage antics — get their gear ready as a restaurant MC holds a dance competition between two half-bored bruisers.

Slowly, the nonrocker presence in the room diminishes as people become either sleepy or fed up. But a few hang around to snicker at the sideshow. Obvious unrest still churns through the mixed crowd. The tension peaks when Black Lips frontman Jared Swilley suddenly grabs an open microphone.

"Can we play now?" he yells defiantly. And the dance-off grinds to a dead halt.

Even without a bunch of indie bands and their fans, music is everywhere on the Imagination. Jazz flute wafts through the bright port terminal. Onboard the 855-foot ship, a pianist plays softly in the glass-ceilinged Atrium Bar. Performers are tucked into alcoves in the neon-and-gold-decorated walkways on the promenade level, and DJs play dance music up on the open-air lido deck.

But on the first day of the Bruise Cruise, just after the ship leaves the Port of Miami, the Xanadu Lounge hosts 450 half-drunk hipsters. The space is a throwback cocktail emporium adorned with golden-winged men, gleaming black tiles, and couches shaped like crescent moons.

Onstage is Ty Segall, a young San Franciscan with a flop of blond hair and an abusive relationship with his guitar. Passengers who aren't part of the Bruise Cruise take a peek and quickly walk away.

Halfway through his set, Segall cedes the microphone to a lanky 25-year-old named Nick Mayor, who sings somewhat inaudibly to a beaming, dark-haired girl standing inches away. Among the Chicagoan's lyrics: "I'd cut off tons of cars and run a hundred lights/If it would get me faster home to you at night/I'd throw away my movies, give up Mountain Dew/When it comes to baby Jen, there's nothing I won't do."

Then Mayor pulls out a diamond, proposing right there to his five-and-a-half-year squeeze, Jen Lemasters. This might be a Carnival first — a garage rock song punctuated with an engagement ring produced from a fanny pack.

The next day, Miami's Jacuzzi Boys shake out the Xanadu's cobwebs via a mind-melting attack. The set attracts bruisers sporting boast-worthy Iggy Pop T-shirts and intricate bird tattoos, as well as a few wet hipsters with towels around their waists.

Continuing the apparently South Florida-themed afternoon is Surfer Blood, the garage rock band from West Palm Beach. And aside from attempting to play "I'm Not Ready" when they really aren't ready (owing to detuned guitars), it turns out to be a mighty midafternoon display.

No one enjoys this performance more than Eric Kolkey. He and his wife Michelle stick out because they're old enough to be the parents of many of the Bruise Cruisers. Back in the '70s and '80s, Kolkey was a promoter and booking agent in Chicago. Once interviewed for You Weren't There: A History of Chicago Punk 1977-1984, he happily recalls shows with the Ramones, the Damned, and the Dead Kennedys. Now the 50-year-old works for the investment firm Rothschild.

This is the first time the couple has been on a cruise. "Not to pump anything up, but we're fairly well-off at our jobs," he says. "We're certainly a demographic the cruise would be more than happy to capture. We're buying lots of booze, spending lots of money. These bands brought us here, and it's worked out for everybody."

For Michelle, the importance is the quality of the bands onboard: "When I go to Pitchfork and Lollapalooza, I always see a lot of bands that I think suck. Why stand around all day seeing a bunch of bands on big stages that you think are lame when you can see these guys who are great?"

"And, of course," Eric butts in, "if you're completely in love with a certain band, like I am with the Vivian Girls —"

"You can stalk them," Michelle says with a glint in her eye.

"It's a crazed fan's dream," he adds. "You're on a boat, and they can't get away."

On Sunday, as the sun drops beyond the horizon, the Imagination is already cruising back to Miami. If there's wine left in the room, this is the time to drink it. And if not, it's time to order the last round.

Around 9 p.m., an employee of a popular music streaming service carries a bucket of Bud Lights into a cabin. Sitting on a bunk bed in the corner, with his sleeve pulled up, the Strange Boys' baby-faced singer, Ryan Sambol, is getting a tattoo on his right shoulder with a pin and ballpoint pen. His new ink spells out "GINA." He jokes that while he's receiving this devotional to her, "She's probably sleeping with some stranger right now."

All the while, Andy Cross, a young man with several similarly homemade tattoos on his arms, sits across from Sambol and explains how he got to the Bruise Cruise from New Orleans by posting flyers around town, meeting a generous woman who had just gotten out of a bad relationship, and persuading her to drive 14 hours.

"Everyone will remember this festival as our Woodstock," Cross adds excitedly.

Soon, though, midnight hits and it's almost time for the final scheduled event of the Bruise Cruise — a semiprivate gathering. The invitation reads, "You are invited... to a very special VIP event... featuring piano playing by Joseph Bradley of the Black Lips."

Wearing a black tux and his hair suavely slicked back, Bradley sits behind the keys, easily the classiest-looking person in this room of haggard, drunken survivors. A few bruisers slip off to quiet corners of the sun deck's fake grass for a make-out session. Others disappear back to their rooms. But Surfer Blood manager Rich Weiss sits at a table near the lido deck bar and contemplatively sips a drink.

"It's 3:42 a.m. on the last night of fucking Bruise Cruise," he says. "I wish this wouldn't end. It's indie rock summer camp. No one wants to say goodbye. We're toasting marshmallows. Except instead of toasting marshmallows, we're drinking Crown Royal out of a bottle. Nothing will quite compare to this first time."