Shanghai - Looking to convince Chinese tourists that a ship can be a holiday destination and not just a way to get there, the world's leading cruise lines are spending billions of dollars on flashy new vessels and quirky on-board services.
Carnival Corp and Royal Caribbean Cruises are trying to pique interest with China-centric attractions such as a menu inspired by an ex-president.
They are also tapping a national penchant for education with classes ranging from foreign languages to silver service.
Drawing cruise lines to China is the prospect of $11.5bn in sales come 2018 compared with $6.8bn last year, according to researcher Euromonitor.
The market will soon be the second-biggest and could eventually surpass the United States, industry executives said.
"Competition is getting increasingly fierce," said Jiang Yushen, a deputy general manager at China's HNA Tourism Cruise Yacht Management Co, part of HNA Group. The challenge is Chinese consumers are still "fuzzy" about what cruising is all about, Jiang said.
Cruises in China tend to last around five days and include stops in neighbouring South Korea and Japan. Global cruise lines have upped investment in the market in the wake of a government initiative last year to develop ports and support local lines.
The year of "marine tourism" in 2013 ended with an almost 20 percent rise in Chinese passengers at 1.4 million - a figure likely to more than triple by 2020, according to data from the government and the China Cruise & Yacht Industry Association.
"The business shot up last year, but this year it is growing even faster," said Wang Yang, chief executive of Youlunhai.com. The travel agent sold around 5 percent of cruise tickets in China last year, Wang said.
Carnival brand Princess Cruises based a ship in the country for the first time in May. Next year, Royal Caribbean will move one of its new near-billion dollar Quantum class ships to China almost straight from the shipyard - unusual as most vessels Western lines base in the country have already been in service.
But as luxurious as the ships may be, cruise lines still have to convince people to get on board at the main ports of Tianjin, Shanghai and Xiamen.
"The biggest challenge is getting the message across to a wider consumer base," Dominic Paul, vice president international at Royal Caribbean, told Reuters.
The cruise line carried 300 000 Chinese passengers last year and targets an annual increase of 70%. It declined to provide investment or sales amounts.
Carnival also declined to specify investment or sales, but said it aimed to increase passenger capacity in the Chinese market by 140 percent from 2013 to 2015.
To lure tourists to the sea - and beat back lower-priced local competition - global lines are working to cater to Chinese tastes, especially when it comes to food.
"Most of our customers start with the same question: What about the food?" said Youlunhai.com's Wang.
Princess Cruises said it offers the only 24-hour buffet in the Chinese market, as well a menu similar to that enjoyed by former President Hu Jintao during a meeting at the White House.
The cruise line also has extra "educational components" with classes in silver service and how to host Western guests.
"Our research found that there was an even greater appetite among Chinese guests to learn," Princess Cruises President Jan Swartz told Reuters.
Youlunhai.com and rival travel agents are also playing their part in growing the market. Ctrip.Com International Ltd , which said it sells around 10% of all cruise tickets, offers discounts through social media platforms and collaborates with dating websites.
Swartz said Princess Cruises had made joint investments in marketing with local travel agents, and gave them discounts for the line's first cruises from its China base.
But there is some way to go to win over tourists like 41-year-old Wu Haifang, who said she was embarking on a cruise simply to get to another country for local food and shopping.
"I just want to go to South Korea and try their pickles, watch Korean TV and buy an electric rice cooker," said Wu, as she waited to board at Shanghai's Wusongkou terminal.
"My husband's company organised a cruise tour for its employees. I got a free ticket just by chance," she said.