Prof. Martin Renilson, a renowned naval architect and marine engineer, conducted a webinar on the topic of Introduction to Submarine Design, on 15^th March 2023. The webinar, hosted by the Marine Engineering Society under the guidance of the department of Marine Engineering with the aim to provide an overview of the principles and challenges of designing submarines, and to highlight some of the latest trends and technologies in this field. During the webinar, Prof. Renilson covered a range of topics related to submarine design, including the historical evolution of submarines, the physical properties and behaviors of water and underwater environments, the hydrodynamic performance and maneuverability of submarines, the structural and material aspects of submarine hulls and pressure vessels, the propulsion and energy systems of submarines, the navigation and communication systems of submarines, and the safety and survivability features of submarines. Significant number of participants including academic staff of the KDU, undergraduates and marine engineers from Sri Lanka Navy participated for this informative session. The webinar included interactive Q&A session where participants asked Prof. Renilson questions about submarine design and related topics. The session was fruitful and Prof. Martin Renilson indicated that he is highly interested to carry out same nature webinars in future.