||Lake Greifensee is surrounded by the most continuous environmental protection area (sanctuary) within the canton Zurich (Switzerland). The lake shelters many national swamps and other biotopes in distress. On beautiful summer days, however, you will find thousands of people spending their leisure time e.g., on mountain bikes, roller skates or swimming. In 1994 a new protection regulation became effective, which allows for intensive utilization and protection of the nature and separates diverse demands. With various measures sanctuaries and recreation areas are spatially separated, and the visitors are guided to keep them off the sanctuaries. During the entire year rangers inform visitors on the possibilities of nature observation, explain them where the recreation areas are located and remind them to keep off the sanctuaries. The number of violations such as trespassing of protected shores and sanctuaries continuously dropped thanks to the effective publicity and the presence of rangers. As a consequence, the vegetation is visibly recovering from the burden of trespassing. To further increase the awareness of the sanctuaries, it is, therefore, important that the rangers continue to regularly supervise the protected and recreational area and to inform and guide the visitors.