Decades ago, the cruise industry paid very little attention to the environment. But cruise lines have spent large amounts of time and money cleaning up their act, and now some are helping to bring sustainable practices to a wider group of players in the travel industry.

“Cruise lines have made quantum leaps when it comes to designing and building ships that incorporate environmentally-friendly practices,” said Carolyn Spencer Brown, editor-in-chief of CruiseCritic.com.

“There is a need to stay ahead of the risk of climate change and sea level rising in the Caribbean and that type of thing. We’re seeing cruise lines making investments to support sustainable destination management.”

For starters, the latest ships are much more fuel efficient than their older fleetmates. “Between Allure of the Seas, which debuted in 2010, and Harmony of the Seas, which comes out next year, our ships have gotten 25 percent more efficient,” said Nick Rose, environmental regulatory lead for Royal Caribbean.

Cruise lines are constantly investing in technological initiatives that move the needle. For example, Royal Caribbean’s newest Quantum-class ships are fitted with air lubrication systems that create a “champagne effect” beneath them.

“Basically, at the bottom of the ship we have four different grates that create very fine bubbles,” Rose said. As a layer of bubbles forms and adheres to the underside of the hull, the ship becomes more buoyant. “This initiative gave us a 5 to 7 percent gain in propulsion. Propulsion takes 60 percent of the total energy of the ship, so a gain of 5 to 7 percent of 60 percent is a very significant amount.”

Meanwhile, onboard water conservation and waste treatment have advanced to the point where the average Royal Caribbean passenger uses 40 percent less water than the average American. And while the average Joe creates four to five pounds of landfill waste every day, the newest Royal Caribbean ships create none.

“Your impact on the environment is not any more than any other kinds of vacations and in some cases might be significantly less on a cruise ship,” said Brian Mullis, founder and CEO of global non-profit Sustainable Travel International.

He said that as cruise lines take the lead in promoting sustainability, they are looking beyond their ships to the places they visit, encouraging onshore tour providers to go green as well.

“At the end of 2014 we had 2,000 tours in 400 ports around the world that had been verified for sustainable practices,” Mullis said.

On a practical note, this simply makes good business sense. Cruise lines “are selling the notion of the pristine island in the Caribbean or South Pacific or wherever it may be,” Mullis said. “To maintain that, destination stewardship practices have to be part of the equation.

“There is a need to stay ahead of the risk of climate change and sea level rising in the Caribbean and that type of thing. We’re seeing cruise lines making investments to support sustainable destination management.”

They’re building relationships with like-minded parties, too. Royal Caribbean is a member of the Sustainable Destinations Alliance for the Americas, a consortium of destinations, local businesses and nonprofits that have a vested interest in protecting natural and cultural resources in the Caribbean. The group, whose members also include Sustainable Travel International, the U.S. government and the Caribbean Tourism Organization, focuses on eight best practices in sustainable destination management in eight countries in the region. 

Priority projects in St. Kitts and Nevis include planting trees in coastal communities to prevent erosion. Those initiatives are now funded in part by contributions from cruise passengers who visit. “I think this is the direction we’ll see the travel and tourism industry move in the future,” Mullis said.

The key to success has been an it-takes-a-village approach to problem-solving. “We have had hundreds of stakeholders involved in each destination – these are key leaders in the private, public, and civil sectors – and some estimated 350,000 lives have been positively impacted thanks to the work completed to date,” Mullis said. “We need to see more of that in the travel industry.”

Suzanne Rowan Kelleher is the family vacations expert at About.com.