This study developed a scale for evaluating how well students understand marine-resource conservation and sustainability; it evaluated the scale's psychometric properties and investigated the gender difference in the scale's score. We recruited 929 university students in Taiwan to answer a questionnaire developed using the scale. The scale's reliability and validity were indicated through psychometric indicators--including Cronbach's alpha, the multitrait-multimethod matrix, and confirmatory factor analysis results. Multiple-group structural equation modeling was used to test the measurement invariance of the scale and to compare the latent mean between the genders. The results of the various analyses confirmed that the scale met the requirements for psychometric assessments. Male and female students significantly differed in the cognitive and behavioral but not socio-emotional dimensions. Scholars can use this scale to investigate how the understanding of marine conservation relates to other factors.