When Emma Le Teace, 25, tried to get her boyfriend to go on a cruise with her, he didn’t want to go. She booked it regardless – and he loved it. “I think he’s been on five now.”

She has been on 21 cruises, and is planning three more this year. “I love visiting new places and, with a cruise, you know your view is going to be completely different each morning when you wake up. A kind of excitement builds up as you get closer to a new destination.”

Once the preserve of retirees, cruises are now seen by millennials as a cool way to enjoy every minute of a holiday, including the time spent travelling to multiple destinations. Market research firm Mintel has found that 38% of those who are interested in taking a sea cruise in the next five years are aged 16-34, while 34% are aged 35-54 and only 28% are aged 55-plus.

“Millennials who are interested in cruises say they like being able to visit many destinations without having to pack their bags, and to make the most of their journey while they are travelling,” said Marloes De Vries, travel analyst at Mintel.

For these passengers, cruise ships provide a rich holiday experience, where the mode of transport is a source of entertainment and there is always something new to see or do. This is important partly because, thanks to the advent of onboard wifi, everything that happens at sea can easily be shared online. Among millennials, De Vries said, “there is a need to show off. Many will still have friends who haven’t been on cruises. It’s new, and undiscovered.”

Facebook Twitter Pinterest Emma Le Teace.

These passengers are hunting for “Instagrammable moments”, says Andy Harmer, UK and Ireland director of the Cruise Lines International Association. Ships hoping to attract younger travellers now offer a wider range of opportunities to learn new skills and to have fun onboard. There may be immersive theatre evenings, boardgame nights, rooftop barbecues, technology lectures and cookery classes using ingredients sourced by passengers in local markets. Transport options ashore can include anything from bicycles and horses to husky sleds and snowmobiles, depending on the destination.

“Cruising is not just about being on a ship and looking at the sea. Millennials want experiences, and to do something different when they go on land,” said Adam Coulter, managing editor of cruisecritic.com.

Instead of just going sightseeing, especially in cities they may have visited before, they want to feel they are on a voyage, enjoying authentic experiences wherever they go. “Cruises tap into a slower way of seeing the world,” he said. “When you put into Hong Kong or Sydney, you can see those cities like they should be seen. You can take time to savour those moments.”

Le Teace, a data developer who runs the blog Cruising Isn’t Just for Old People in her spare time, thinks activities encourage young people to be sociable. “You can be entertained every minute of the day. Everyone always seems to be in a good mood and I’m happy too. I think that’s partly why it’s so easy to make friends. I’ve worked in my office for four years, and I don’t know people there as well as people I’ve met on a cruise.”

Cruise ships have been criticised by Greenpeace for producing as much pollution as a million cars. Many currently run on fuel oil, which contains about 2,000 times more sulphur dioxide than ordinary diesel. But in 2016, the International Maritime Organisation announced a global cap on sulphur emissions, requiring ships to either use greener fuels or install exhaust gas cleaning systems to reduce the toxicity of their emissions from January 2020.

“The new ships are really trying to be more environmentally friendly,” said La Teace. “Obviously it does have an impact, but if you take all the people off a cruise ship and put them in a plane or a car, I think it would be worse for the environment.”