As the world is keen on technological advancement, the maritime industry has also seen its fair share of development. The Maritime Autonomous Surface Ships (MASS) stand as proof of the novel innovation done in this industry, as they autonomously navigate through the big blue mass of water, utilizing the advanced set of communication technologies, sophisticated set of Information Technologies (IT), and Operational Technologies (OT) networks. With the introduction of an integrated combination of navigation systems, engine systems, complex control algorithms, and sensor technologies to enable remote monitoring and operation, these technological breakthroughs have altered the traditional marine ship architecture and given birth to unmanned autonomous ships. In this thesis, we explore the distinct combination of ICT and OT that make up the architecture of MASS and emphasize the interdependence and complex network among these components, which might result in potential possibilities for cyber threats. It also presents a comprehensive analysis of threat modeling, which we have considered crucial in fortifying MASS from cyber threats. The thesis describes the process of developing threat models tailored to MASS's environment, focusing on the MASS infrastructure, threat actors, and resources, identifying and addressing vulnerabilities. Ultimately, this thesis believes a thorough proactive approach to creating a threat modeling framework, together with an awareness of cyber-security and its preparedness, is critical in protecting MASS from cyber threats and saving a whole sum of money for the maritime industry. Through continual innovation and strategic partnership, the maritime sector can navigate toward a safe future while guaranteeing MASS autonomy and contributing to effective marine operations in the great blue oceans.