When U by Uniworld launched her new ship, The A in Amsterdam last weekend, there were 16 Australians on board.

And while some certainly just slipped into the definition of millennial, most were in their mid-30s to mid-40s.

They were among the 90 passengers on board the ship, said Fiona Dalton, managing director of Uniworld in Australia.

Originally debuting as the first cruise line for millennials aged from 21 to 45 years of age, U by Uniworld has been forced to drop the age limit.

“It was a really hard decision for us to drop the age limit,” Ms Dalton said.

“How many times can you tell guests that we have an age limit of under 45. So we listened to our customers. Age is not a number, it is really a mind set.”

Now baby boomers have been belatedly allowed to travel on U by Uniworld and experience the ship’s silent discos, Ibiza-inspired rooftop terrace and smoothies served at communal tables as river ship stops at some of the world’s hippiest cities including Berlin and Amsterdam.

Ms Dalton also said that more Australians are taking to Uniworld’s river cruises in Vietnam, Cambodia and India.

“Our Australian numbers have doubled from last year with more travelling with Uniworld to Vietnam and Cambodia. Our river cruise on the Mekong Navigator combines a 7-night cruise with a 7-night land component.

“In India, we have seen a 52 per cent growth in the number of Australians cruising on the Ganges compared to last year. Bookings for this year are almost full. Our ship, Ganges Voyager II is really a five-star floating hotel for 56 guests. Our voyages also combine a land component where guests are able to stay in New Delhi, Jaipur and Agra.”

Uniworld is also introducing more immersive itineraries in India next year as guests want to participate in volunteerism and give back to the community.

At the start of their cruise holiday, passengers will spend four days as volunteers and work with a local community on a building project or farm.

In China, Uniworld will introduce the newly refurbished Sanctuary Yangzi Explorer for its 3-night cruise on the Yangtze River next year. The Highlights of China and Yangtze itinerary includes a 7-night land tour.

Meanwhile, Uniworld is offering free economy flights for every European voyage departing before November 15 next year. Guests can upgrade to premium economy seats for $1,299 per person or business class for $3,999 pp. The upgrades are only available until 30 June.

“We’re including return economy airfares to Europe on all our 2019 sailings departing before 15 November 2019. This is an extraordinary offer designed to make the Uniworld difference truly accessible to all Australians,” said Ms Dalton.

The fly free to Europe offer is available for bookings made before June 30 this year.