This study investigated the teaching pedagogies deployed in teaching environmental science (ES) to adequately prepare Bhutanese youth with the knowledge, values, attitudes and skills to engage in sustainable environmental conservation that supports the country's pursuit of Gross National Happiness. A mixed-method research strategy was employed that collected data in the form of surveys and interviews with 14 teachers, surveys with 563 students, interviews with 194 students through (46) focus groups and six classroom observations. The data indicated that the transmissive approach (teacher talk), discursive activities (presentation and group discussions), and textbook-based activities of reading and solving problems from ES textbooks are the most predominant teaching approaches implemented in teaching ES. Students are engaged in critical thinking, empirical real-world and book-based research and maintaining an environmental profile; however, there is a lack of hands-on activities of projects, experiments, fieldwork, exhibitions and surveying and interviewing people. Teachers identified that lack of time, examination-based assessments, the large syllabus and a lack of resources are the factors that impede learning activities in ES. Therefore, there is a need for more emphasis on teachers' professional development on transformative teaching pedagogies for effective implementation of ES that will prepare students for the pursuit of environmental sustainability.