Some companies specialise in ecotourism, designing the trips to be environmentally, culturally and socially friendly. Companies such as Intrepid Travel, frontier, and Marine Conservation Society, Peregrine Adventures, World Expeditions, Explore Worldwide and Exodus offer trips catering for the thoughtful traveler. Some tour operators are keenly aware of the impacts that they may have on specific areas and rotate clients around to different sites for snorkeling, bird watching, and other activities. Others are just beginning to see the advantage of "green" travel destinations.