The purpose of this paper was 1) to investigate the effects of CBI training on awareness and content knowledge to investigate the English knowledge of young people involved in mangrove forest conservation and ecotourism, and 2) to investigate the perception of young people on the importance of mangrove forest and natural resource conservation and ecotourism. The study was designed to implement a pre-test, post-test and satisfaction questionnaire as research instruments. The data was analysed by content analysis, Mean, and standard deviation. Forty high school students (Grades 10-12) volunteered to participate in the training course. The itinerary included a two-day course comprising lectures, workshops, and a field trip. The findings revealed that participants who attended the training course had significantly improved their language abilities at a 0.01 level. The Mean was at 4.32 on four issues (usefulness, knowledge, lecturers, places/duration/media) and their overall satisfaction received a high approval rating. The participants indicated that their English ability had improved and their knowledge about natural resources and conservation had developed. The results show that this course could be beneficial for both young people and others who are also interested in sustainable ecotourism and environmental conservation in general.