The network of organizations promoting sustainable traveling is growing, and that's good news for the most sacred and endangered travel destinations around the world.

The United Nations' World Heritage Alliance announced nine new members, including the Rainforest Alliance. The WHA is "committed to promoting sustainable tourism that contributes to the conservation of local biodiversity and cultures and creates opportunities for local community enrichment..."

Members work with local merchants such as hotels and tour operators to include cultural activities as part of tourism that protects the 830 designated World Heritage sites, such as the Machu Picchu in Peru and the Great Barrier Reef in Australia. The Rainforest Alliance has created a handy search tool for finding sustainable businesses.

Travel website Expedia is doing its part to protect these sites by offering special ecotourism packages and giving a percentage of the profits to the WHA. These trips give visitors insight into the local cultures and provide a more rewarding experience.

The landmarks are increasingly suffering the effects of global warming, according to a new report by the WHA.

Future generations deserve an opportunity to experience these timeless treasures, so it is encouraging to see Expedia and other organizations supporting travel that minimizes the environmental impact.