Algal bloom is a naturally occurring phenomenon and occurs in all waters around the world but in recent years, algal bloom in the Baltic Sea has become more massive and more widely spread. When an algal bloom negative effects on the seawater quality, it may have an impact on tourism in the Baltic Sea. The aim of this thesis is to study, through a survey based on a production function approach, whether an environmental change as algal blooms, influenced the Gotland tourist accommodation industry and their "production of attractive overnight? in the summer of 2005. The results show that algal blooms did not have a great impact on companies ?production of attractive accommodations".