Some of the best wildlife cruises are packaged by Oceanic Society Expeditions (tel. 800/326-7491; Whale-watching jaunts and some research-oriented trips are also featured. You can swim with humpback whales in the Dominican Republic, for example.

Puerto Rico's varied and often hard-to-reach natural treasures have been conveniently packaged into a series of affordable eco-tours. AdvenTours (tel. 787/530-8311; features customized private tours with activities like bird-watching, hiking, camping, visits to coffee plantations, and kayaking. Aventuras Tierra Adentro, 268 PiƱero Ave., San Juan (tel. 787/766-0470;, specializes in rock climbing, body rafting, caving, and canyoning, among other activities. Eco Xcursion Aquatica, Road 191, Km 1.7, Rio Grande, Fajardo (tel. 787/888-2887), offers some of the best rainforest hikes and mountain-bike tours.

Machias Adventures (tel. 888/427-3497 or 203/454-1243; arranges adventure tours to St. Vincent, including hiking up a volcano, sailing with a crew, seeking out the huge variety of bird life, and hiking up a river canyon to a dramatic water pool -- perfect for swimming. The cost of these 7-day jaunts is $2,500 per person, based on double occupancy.

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.

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.