The lack of interest among pre-university students to choose STEM subjects for their higher education is a heavily debated issue in many western-world countries. To boost Danish students’ interest in biology, a study event on artificial reefs was introduced when teaching marine biology in lower secondary school and upper secondary school (student age 13–20 years). The purpose was to investigate if the focus on artificial reefs could generate an increased interest in natural science and marine biology among the students. The students’ interest in science was evaluated using electronic questionnaires before and after they had completed the teaching programme. The students were significantly more interested in natural sciences and marine biology after than before the teaching program. The development in situational interest in science and in the oceans was different for males and females with females being most interested. Thus, it is possible to trigger a situational interest for science and marine biology by teaching about artificial reefs, but the way interest is triggered differs between different age groups and sexes.