Mainstream tourism is relatively unspecialized. The tourist who wants to "get away" but doesn't have any specific desires to see a particular area or be involved in particular kinds of activities while on vacation is looking for a mainstream kind of experience. There are no critical requirements for the trip - the goal is to simply go somewhere new or different and engage in activities other than the routine ones for the traveler.
Special interest tourism covers the whole range of travel possibilities that focus upon some particular area or interest. A tourist who wants to spend his/her vacation studying the lifestyle of a particular type of animal may choose to go on a trip to the area where that animal lives, using the services of a guide to locate and learn more about the creature. Tourists who are committed to environmental issues may choose to spend their vacation working to rebuild eroded trails, clean polluted waters or shores, or collect samples of soil or water for testing and evaluation by sponsoring scientific groups. Tourists who want to experience new or extreme activities may vacation with others while climbing mountains, biking extraordinary distances or locations, scuba diving in remote areas, or other activities that are not easily arranged.