State Tourism Minister Kodiyeri Balakrishnan said the rating by National Geographic Society's Center for Sustainable Destinations has come as a shot in the arm for the industry.

"We will make this new certification as our USP. We have now finished a series of road shows in Europe and our next round of road shows in Italy, France, and Australia will take place. We will make this certification our main campaign point," Balakrishnan told IANS.

Over the years Kerala's tourism industry has recorded consistent growth. In 2008 there was 14.84 percent growth in tourism revenue while tourist arrivals grew 14.41 percent over 2007.

But the tourism sector in Alappuzha, known for its houseboat tourism and which earned this certification for the industry, wants urgent promotional steps by the government.

Tomy Pulikattil, who owns a fleet of houseboats including those that can accommodate more than 100 people, said after the Thekkady tragedy the tourism season appears to have dried up. At least 45 people had died when a boat overturned in Thekkady.

"The government has to launch a series of promotional activities because the fear of Thekkady still lingers in north India. The truth is that never has a tragedy occurred in the houseboat industry. A houseboat can bear a load from 30 tonnes to a maximum of 120 tonnes and the design of a houseboat is totally different to that of a motor boat," said Pulikattil, who recently conducted an inclination test by a marine expert on all his boats.

Kerala's peak tourism season begins mid-November and extends till March.