This study investigated the quantitative risk assessment of the naval ships operating within Niger-Delta, Nigeria. Descriptive and analytical research designs were adopted. Three accidents prevalent in naval ships and the associated hazards that caused these accidents were identified using the Nigerian Navy safety ledger (2010-2019). The accidents are Slip and fall accidents, Electrical accidents and Mooring operation accidents. The risk assessment was conducted by ranking of the hazards based on their risk rating using Conventional Risk Assessment (CRA) which involved multiplying the likelihood of the hazards to cause harm and the severity of the harm when it occurs. The severity and likelihood of the hazards were obtained using questionnaire and the respondents were forty-four (44) principal officers in the Eleven (11) naval ships. The results obtained were used to carry out Fault Tree Analysis (FTA) and the final outcome of the FTA revealed that the three main causes of these three accidents were poor management, lack of safety awareness and consciousness and violation of rules of safety on-board. It was then recommended, among others, that safety managers on-board naval ships should organize safety workshops for naval personnel to improve their safety awareness. Given that all the prevailing accidents, naval ships and major naval officers were not involved in this study is the major limitation of this study. It is recommended that more studies be carried out using other risk assessment tool like the Fuzzy Analytic Hierarchy Process (AHP).