Each time you take a flight or drive a car, carbon dioxide (CO2) is released into the atmosphere. You can help neutralize this danger to our planet through "carbon offsetting" -- paying someone to reduce your CO2 emissions by the same amount you've added. Carbon offsets can be purchased in the U.S. from companies such as Carbonfund (www.carbonfund.org) and TerraPass (www.terrapass.org), and from Climate Care (www.jpmorganclimatecare.com) in the U.K.

Although one could argue that any vacation that includes an airplane flight can't be truly "green," you can go on holiday and still contribute positively to the environment. You can offset carbon emissions from your flight in other ways. Choose forward-looking companies that embrace responsible development practices, helping preserve destinations for the future by working alongside local people. An increasing number of sustainable tourism initiatives can help you plan a family trip and leave as small a "footprint" as possible on the places you visit.

Responsible Travel (www.responsibletravel.com) contains a great source of sustainable travel ideas run by a spokesperson for responsible tourism in the travel industry. Sustainable Travel International (www.sustainabletravelinternational.org) promotes responsible tourism practices, issues an annual "Green Gear & Gift Guide," and has a sustainable travel blog.

You can find eco-friendly travel tips, statistics, and touring companies and associations -- listed by destination under "Your Travel Choice" -- at the International Ecotourism Society website, www.ecotourism.org. Ecotourismlogue.com is part online magazine and part eco-directory that lets you search for touring companies in several categories (water-based, land-based, spiritually oriented, and so on).

In the U.K., Tourism Concern (www.tourismconcern.org.uk) works to reduce social and environmental problems connected to tourism and find ways of improving tourism so that local benefits are increased.

The Association of British Travel Agents (ABTA; www.abta.com) acts as a focal point for the U.K. travel industry and is one of the leading groups spearheading responsible tourism.

The Association of Independent Tour Operators (AITO; www.aito.co.uk) is a group of specialist operators leading the field in making holidays sustainable.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.