This study adopted a quasi-experimental design to examine the effect of implementing outdoor marine education at the National Museum of Marine Science and Technology (NMMST) on university students’ knowledge, attitudes, and behaviors. Among the 151 students participating in the study, the 80 who were enrolled in the course “Environmental Education” were designated as the experimental group, and the other 71 enrolled in the course “Environmental Safety and Health Protection” were designated as the control group. The experimental group was involved in outdoor learning activities at NMMST, while the control group did not participate in outdoor learning activities at NMMST. The research instrument for this study was a self-developed knowledge, attitude, and behavior questionnaire. We implemented this questionnaire for the pre-test and post-test of the experimental group and the control group, and then performed statistical analysis based on the data obtained from the pre- and post-tests. We also analyzed qualitative data from worksheets and interviews. The results show that, first, the outdoor marine education teaching at NMMST is effective at improving the knowledge, attitudes, and behavior of the experimental group students. Second, the correlation analysis reveals that for the experimental group of students, the correlation between knowledge and attitudes is low, there is no correlation between knowledge and behaviors, and there is a moderate correlation between attitudes and behaviors. We conclude that the integration of outdoor teaching at NMMST into the environmental education curriculum could enhance university students’ marine knowledge as well as attitudes and behaviors towards marine environmental protection, thereby enhancing the effectiveness of marine education. We suggest when teachers implement outdoor teaching at NMMST that, they should make good use of guided tours to enhance students’ interest in learning and learning outcomes.