Tourism is largely responsible for knowing the need for sustainable development because it is most interested in the sustainability of all resources that are the foundation of its development. The application of the concept of sustainable development in tourism should ensure that uncontrolled development does not destroy the resources on the basis on which tourism has begun to develop in a given area. Sustainable development of island tourism is becoming more and more significant. In Croatia there is insufficient focus on sustainable development of island tourism. In some parts of Croatia, the importance of sustainable tourism for the development of tourist destinations is still not sufficiently recognized. Therefore, the features of tourism of the island Krk have been explored through this paper as well as the problems that arise, related to the sustainability of development and the activities that need to be undertaken in order to develop Krk's tourism in accordance with the principles of sustainable development. For research purposes, a survey with tourists and interviews with representatives of tourist boards and OPG’s of the island Krk were conducted. Based on the results obtained, it was concluded that the sustainable development of tourism on the island Krk has been significant for a number of years. The development of sustainable tourism on the island Krk started in 2005, and also a few years ago the Development Strategy for the island Krk has been developed. The Strategy defines goals and activities for ensuring sustainable tourism development. Some of these activities have already been successfully implemented and have shown positive results. The island of Krk is one of the most important islands that can help with its examples and other islands in the development of tourism sustainability. The island Krk with its examples of successful sustainable development of tourism can help other islands in the development of tourism sustainability.