Some 13 million eco-tourists fueled the $2-billion industry in 2009.
The whale-watching industry generated $2 billion in revenue last year.
Whale tourism could add more than $400 million and 5,700 jobs to the global economy each year.
The findings boost arguments that the marine mammals are worth more alive than dead.
Whale-watching revenue topped $2 billion in 2009 and is set to grow 10 percent a year, according to a new study.
The findings boost arguments that the marine mammals are worth more alive than dead, the researchers said.
They also coincide with a decision by the 88-nation International Whaling Commission (IWC), meeting in Agadir, Morocco, to move forward with a "five year strategic plan" exploring the economic benefits and ecological risks of whale-watching.
Some 13 million eco-tourists in 2009 paid to see the animals in their natural element, generating $2.1 billion and employing 13,000 people across hundreds of coastal regions worldwide, the study found.
"This shows that we can have our whales and still benefit from them, without killing them," said co-author Rashid Sumaila, a researcher at the University of British Columbia.
Whale tourism has expanded steadily over the last two decades, and could add more than $400 million and 5,700 jobs to the global economy each year, said the study, published in the peer-reviewed journal Marine Policy.
"Given our methods of calculation, this is a conservative estimate. The real figures are probably much higher," Sumaila said by phone.
At least half of this growth would benefit seaside communities in developing countries, especially in the Caribbean, Latin America and Africa, where many fisheries are in decline.
"It can be launched with little initial investment and carried out by local fishers who are already familiar with the area," the study noted.
Whaling countries have argued that watching whales and killing them are not necessarily incompatible when populations are robust and expanding.
Indeed, every year half-a-million people ply the coastal waters of whaling nations in the hope of glimpsing a humpback, orca or other whale if full breach.
But if attitudes continue to shift toward protection, the researchers suggested, tourists may one day insist on observing whales near countries that are not also engaged in slaughtering them for market.
An effort to bridge the gap between pro- and anti-whaling nations during the IWC's annual meeting, which ends Friday, collapsed earlier this week.
Despite a moratorium on commercial whaling that went into effect in 1986, Iceland, Japan and Norway -- taking advantage of legal loopholes -- harvest hundreds of large cetaceans every year, more than 1,500 in the 2008-2009 season alone.
Opponents of commercial whaling hope that tourism will help tilt an organisation created in 1946 to insure the long-term viability of the whaling industry toward other goals.
"All international bodies must evolve," said Peter Garett, Australia's minister for environment protection. "We see a future for the IWC that is much more about conservation than counting the number of whales that are killed."
"There is a tremendous economic future -- a sustainable future -- in whale watching, not whale killing," he told AFP.
Many local communities are thriving thanks to mammoth sea mammals that happen through their waters, delegates said.
The New Zealand town of Kaikoura, for example, "has subsequently been transformed, and now attracts 100,000 visitors annually," said Kerena Lyons.
And in tiny Samana Bay in the Dominican Republic, "43 boats and 10 tour operators offer trips for more than 25,000 tourists every year," said Liliana Betancourt of the Conservation Centre of Bahia de Samana.
But whale-watching can have unintended consequences, warned Vincent Ridoux, a marine biologist at the University of La Rochelle in France and a member of the French delegation.
"We tend to observe whales where they feed and reproduce. If the whale-watching is too invasive and always in the same place, it can push the whales into less optimal areas," he explained.
But perhaps the greatest danger is running out of whales.
"It could be a multi-million dollar industry, but in Tonga there are not enough whales anymore," Sue Taei of the Pew Environment Group said of the Pacific island nation.
The region's whales were decimated by Soviet factory ships in the 1960 and 1970s, she explained.