This study aims to determine the opinions of prospective biology teachers about outdoor learning environments by drawing on the cases of museum visit and scientific field trip. In line with this aim, phenomenology research design was utilized. Criterion sampling, which is one of the purposeful sampling methods used in qualitative research studies, was resorted to with a view to determining the participants. In accordance with the phenomenology of the research, 17 prospective biology teachers in their first year of their studies during 2018-2019 academic year in a public university constituted the participants of the research. In order to determine the opinions of prospective biology teachers about outdoor learning environments, an opinion form and an observation form were made use of as data collection tools. Content analysis was referred to in the analysis of research data. In their views on the contributions of the outdoor learning environments, prospective teachers seemed to concentrate on the issues of gaining new information, concretizing the knowledge, learning in the natural environment, and learning by doing and living. It was understood that the codes of "following the guide/teacher", "acting in a planned manner" and "practice" came to the fore in the opinions of the prospective biology teachers regarding the things to be done during the implementation phase of the outdoor learning environments. While the codes of "getting opinion" and "question-answer method" came into prominence in the prospective teachers' views on the things to be done in the evaluation of outdoor learning environments; especially due to its content, after the scientific field trip, prospective teachers expressed opinions about "the examination of the notes taken, pictures, samples, and so on." It was also observed that codes emerged from the suggestions of prospective biology teachers regarding the use of outdoor learning environments focused more on these aspects of the process: "should be a well-planned trip", "should be informative", "time management" and "participant/ teacher characteristics".