As climate change guilt among tourists grows, hotels and resorts are finding they need to do more to please the green consumer than simply ask them to re-use their towels.
Under-sea air cooling systems, intelligent lighting, organically-fertilised herb gardens and spas constructed entirely from mud are all being employed to woo tourists concerned about their carbon footprint.
Businesses are also realising that environmentally-friendly policies are not only good for their conscience, but their wallets and reputations too.
"Now the environment is very important for people," says Nantiya Tulyanond, owner of the Old Bangkok Inn, a small hotel in the Thai capital with an impressive range of energy-saving technologies.
"I think it is very important, not to save the world, but to save the money as well."
At the Six Senses Hideaway just south of the Thai seaside resort town of Hua Hin, staff in airy pyjama-like uniforms zip around the 30-acre (12-hectare) resort on bicycles under the shade of palms and banana plants.
Guests relax in private villas built from locally-sourced materials. Hardly anything in the room is plastic, and a leaflet encouraging guests to offset the harmful gases emitted by their flights sits by the bedside.
Srichan Monrakkharom, the resort's social and environment manager, enthuses about the mushroom farm, mud spa, herb gardens, solar water heating, and air conditioning systems which switch off if guests leave their doors open.
"European people, they feel guilty that they have to fly a long way and generate a lot of carbon emissions," says the environmental science graduate.
A United Nations report last year found that tourism, in particular air travel, accounted for about six percent of global emissions of carbon dioxide -- the main greenhouse gas that traps the sun's heat and fuels global warming.
And with the number of global travellers predicted to double by 2020, emissions also look set to increase.
Six Senses guests Will and Lyn Swayne, both in their early 30s, work in advertising in Hong Kong and try to research a resort's environmental credentials before booking in.
"What we are trying to do at the moment is cut down the amount of travel that we do, going on less holidays," says Will Swayne.
Many guests, however, say they simply do not know how to research a resort's eco-policies.
"It's always hard to judge when you are far away from the place -- you have the marketing materials but you wouldn't always know what was going on," says Geoff Thompson, 34, a computer programmer from New Zealand.
A search engine request for "eco-resort Thailand" comes up with about 34,000 results, with the "eco" prefix sometimes meaning just that the resort is built on a pristine stretch of beach or offers adventure travel.
There are resources for eco-conscious travellers such as the website EnvironmentallyFriendlyHotels.com and the private Green Globe 21 certification given to resorts that meat certain criteria.
But Oliver Martin, an associate director at industry body the Pacific Asia Travel Association, says there are so many different "green" standards on the market right now that tourists are left scratching their heads.
"Consumers will want to know more and they will want to know that the dollars that they are spending are actually making a difference, but right now it is the Wild West," he tells AFP.
European travellers in particular are demanding more from hotels than token efforts toward the environment, he says, meaning the travel industry needs to adapt and grow in a sustainable way.
Michael Kwee, social responsibility manger for the upmarket Banyan Tree Hotels and Resorts, says the Singapore-based chain is on the verge of announcing a company-wide water management and energy efficiency policy.
Six Senses even toyed with the idea of cooling their new Thai resort by piping cold air from under the sea -- only to find that the nearby waters were not deep enough for the innovative green technology.
Back at the cosy 10-room Old Bangkok Inn, Nantiya enthuses about the little things modest hotels can do to help save the environment.
Low flush toilets, energy-saving appliances, sky lights making use of Thailand's abundant sunshine and furniture made from salvaged wood all help her hotel go green while cutting the energy bills in the long run.
"We love to be with nature, we love flowers, we love trees, we love animals -- and I think all the green things go together with this," she says.