Since the 1940s scuba diving tourism has become popular all over the world, however, this demand also has brought human-driven negative impacts on underwater surroundings. Reducing adverse effects on the marine environment and maximising the unique scuba diving experience depends on long-term socio-economic benefits and protecting natural and alternative marine resources. Over the last decade, system-based approaches have been developed by researchers to examine the interaction of scuba diving activities. However, a better understanding of principles of sustainability and practices and having a broad knowledge about how these are based on normative aspects can provide advantages for stakeholders in the system to reduce negative impacts. Therefore, this thesis aims to redesign the scuba diving tourism system thorough defining the normative aspects based on principles of sustainability. Investigating the research question “to what extent do the normative aspects of the scuba diving tourism system address principles of sustainability”, this study uses an interpretive paradigm as the phenomenological qualitative research method. As a destination that has developed a distinctive but significant scuba diving tourism sector, the main research took place in the Mediterranean archipelago of Malta using face to face interviews with stakeholders and in-situ observation via active participation. As a result, a new systems approach as `Sustainable Scuba Diving Tourism System` (S-SDTS) is proposed which is redesigned based on normative aspects founded on principles of sustainability.