Whatever floats your boat - the unstoppable growth of themed cruises

Kiss typically perform two shows per cruise

Show-stopping rock band Kiss were always going to go the extra - nautical - mile.

Not content with filling stadiums around the world, and selling more than 100 million records, the face-painted, fire-breathing US hard rockers also have their own navy.

Every autumn Kiss hire a huge cruise liner to sail around the Caribbean for a week with 2,300 of their diehard fans. This year will be their sixth voyage, or Kiss Kruise VI.

The band perform two shows on the ship, and fans get to meet and hang out with the four band members.

There are 13 bars on board, plus 12 restaurants, a swimming pool, a gym, a spa, a casino, an indoor theatre and a tattoo parlour for getting a new Kiss ink work.

Each Kiss Kruise sets sail from Miami

Members of the so-called Kiss Navy fly into Miami from around the world to attend, and Kiss vocalist and bass guitarist Gene Simmons says the cruise is one of the highlights of his annual calendar.

"It's rock and roll all night and party every day," he says. "Anyone who has ever been on one of our cruises comes back raving to their friends.

"Imagine 2,300 crazy friends, swimming, shopping, gaming and visiting exotic ports of call with us."

Kiss perform both with and without their famous face paint on the cruise

While Kiss might not be to everyone's taste, the rock group has helped to transform the once staid world of cruise lines.

Whereas cruises were traditionally the preserve of elderly holidaymakers, over the past decade - and especially in the past five years - there has been an exponential growth in the number of "themed cruises" - cruises aimed at people with a specific interest.

This has opened up the world of cruising to a much younger demographic, and given the cruise industry hundreds of millions of dollars in additional earnings.

Gene Simmons will even officiate at fans' weddings on the sailings

Some Kiss fans get a new tattoo on the cruise

From music cruises - at which Kiss are leading the way - to cruises for people with specific political views, or cruises for poker players, or fans of Italian food, there is a ship sailing for pretty much everyone.

For example, if you are passionate about your constitutional right to bear arms, you might be tempted to join the Freedom Alliance and National Rifle Association's cruise down the River Danube in June. Guest speakers include US Republican politician - and former speaker of the US House of Representatives - Newt Gingrich.

Or if you are transgender, Transgender Vacations organises cruises around the Caribbean.

Disney holds regular sailings for fans of the Star Wars movies, where you can dress up as a stormtrooper or ewok and meet some of the actors.

'Intimate environment'

Howard Moses, founder and president of the Cruise & Vacation Authority, says that more than 700 themed cruises now set sail around the world each year, compared with less than 30 a decade ago.

"Themed cruises are absolutely by far the biggest growth area in the industry," says Mr Moses, whose organisation is based in the US state of Georgia.

Music cruises are not just about listening to your favourite band

"It has enabled the cruise industry to reach beyond people who are our traditional customers, to people who are passionate about a certain subject.

"For music cruises, there can be a very young crowd.

"And for the political cruises we joke that the attendees are often people who said they would never go on a cruise, yet they have the time of their lives, and are the first to lead the conga line."

Rock band Paramore is another group which sells cruises

At Atlanta-based Sixthman, the world's largest organiser of music cruises, its communications manager Alaidriale Derway says the business has just wrapped up its busiest ever spring sailing season, with 10 back-to-back cruises.

Sixthman now has more than 500 acts on its books, including Kiss. Other acts for whom it organises cruises include Weezer, Paramore, Lynyrd Skynyrd and Kid Rock.

The company charters the ships and helps to organise support acts.

Kiss fans also get to meet their idols

Ms Derway says: "More and more artists want to get involved.

"Cruises are a great way for artists to interact with their fans in a much more intimate environment, and collaborate with each other.

"In terms of the cost for a fan, they pay a set fee, and then pretty much everything is free except for alcohol and soda. All the food is included unless someone wants to pay for more speciality dining."

She adds: "Lots of people really hesitate to do the whole cruise thing, there is still a bit of a stigma attached, but you can really connect with people who are passionate about the same things as you are."

Game of Thrones fans can now visit its British Isles sites via cruise ship (and a connecting bus)

While the music cruise industry is very much based in the US, themed cruises are also a growing phenomenon on the other side of the Atlantic.

Mike Bugsgang, chief executive of the UK-based Association of Group Travel Organisers, says there has been a big rise in the number of cruises that include visits to locations that have featured in well-known movies.

One such cruise organised by Fred Olsen Cruise Lines is called "UK Scenes from the Silver Screen". Sailing around the UK and Ireland, the itinerary includes trips to settings from TV series Game of Thrones and the Harry Potter movies.

Sixthman uses vast ships for its music cruises

Back in the US, Kiss' Gene Simmons doesn't just have to prepare for performing live on the Kiss Kruise, he also has to brush up on his wedding officiating. An on-board extra for Kiss' hard-partying fans is the chance to splice more than just the mainbrace. They can tie the marital knot, with Mr Simmons or a fellow band member performing the service.

But one thing a Kiss Kruise is not is restful.

As Mr Simmons admits: "It's tough to get to sleep on the cruises... it is fair to say, both the band and the fans are completely exhausted once we leave the cruise."