Whalewatching revenue topped $2 billion in 2009 and is set to grow 10 per cent 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 whalewatching.
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," Mr 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.
But if attitudes continue to shift towards 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 ended yesterday, 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.