Traditional forms of tourism, particularly mass tourism to resorts and beaches, have well-documented detrimental effects on the regions and countries visited, ranging from marine population. In the last decade sustainable tourism and ecotourism have been vaunted as answers to the problems of mass tourism and as a contribution to conservation of the world’s wild places and the welfare of indigenous people. This chapter will examine the theory and practice of ecotourism and sustainable tourism with particular reference to national parks and other protected areas in Indonesia.