Unlike conventional cruises, with nights spent at sea and days in coastal ports, river trips allow more time for exploration as they sail on much smaller ships through cities such as Vienna, Paris, Mandalay and Ho Chi Minh City.

'Seeing several cities in Europe's interior can sometimes be difficult in one vacation,' says Leung. 'River cruises on the Danube and Rhine, for example, allow guests to experience a new city ... every day of the trip.' With no 'sea days', as are common on ocean liners, river cruises appeal to travellers who want to see as much as possible.

Ecruising says passengers booking river cruises are typically 55 years old or older, financially secure, well travelled and looking for new experiences. They are also more interested in on-shore activities than onboard entertainment, making smaller ships departing from major cities a better fit.

David Leung of JJ Explorer Tours has also seen an increased interest in river cruises. Among the attractions, he says, is a new ship on the Mekong, RV La Marguerite, which takes passengers from Saigon to Phnom Penh in seven days with many stops along the way.

'River cruising is making a comeback and the new luxury vessels cruising the Mekong, including La Marguerite, combined with cheaper airfares to destinations such as Vietnam, make river cruising a no-brainer,' David Leung says. 'River cruising is a much more intimate style of cruising, with the countryside sometimes only metres away and far fewer passengers. You get a much better sense of place than you do with ocean liners.'

He says cruises typically appeal to older people who have more free time as many trips run longer than a week. But because major cities and key attractions tend to be built along large waterways, river cruises are shorter and more action-packed.

He says that the cruises have proven popular among couples, especially those in their 40s and 50s, looking to escape the city for a short getaway.

The La Marguerite is a 46-cabin vessel named after French writer and filmmaker Marguerite Duras, who grew up in Indochina. Launched in July, the ship features timber interiors, a plunge pool and a cane rooftop lounge.

Making its return is Orient-Express' 56-cabin Road to Mandalay vessel, which has emerged from a 12-month restoration after sustaining damage in last year's Cyclone Nargis.

'What better way is there to discover Myanmar than sailing between Bagan, with its 2,500 pagodas and temples, and Mandalay, the ancient capital,' asks Yann Guezennec, Orient-Express' global director of sales and marketing.

The former German river cruiser, which began sailing in Myanmese waters in 1995, offers modern en suite cabins, while the restaurant serves seven different types of cuisine: Myanmese, Shan, Thai, Indonesian, Chinese, Indian and European.

'Myanmar is probably the most fascinating country in Southeast Asia, and remains remote from traditional tourist paths considering its vast variety of sites,' Guezennec says. The number of cabins was reduced in the vessel's restoration from 108 to 82 offering more cabin space, a better passenger-to-staff ratio and a more intimate cruise experience, he says.

Cruising the Three Gorges offers a chance to explore the mainland's arts and culture and also to see the new dam's towering 101-metre wall. Sanctuary Cruising's newest vessel, the Yangzi Explorer, features 38 deluxe cabins and 24 suites, all with private balconies, and is one of the smallest vessels cruising the gorges. Five-day sailings between Yichang and Chongqing take passengers through the dam's ship lock system, passing below the dam's wall, as well as the 76km-long Xiling Gorge and Huangling Temple.

Outside Asia, traditional routes for river cruises remain popular such as the Rhone, Rhine, Seine, and Danube, which pass through some of Western Europe's most picturesque scenery. Carrying just 140 passengers, the new Avalon Creativity offers eight-day Paris to Normandy round-trip cruises, exploring the French capital and also touring tranquil provincial riverside villages and historic second world war landing beaches.

'Hongkongers will always love cruising Europe - we're romantics at heart and it's such a contrast from home,' says David Leung.