Marine incidences and casualties result in occurrences like loss of lives, personal injuries, collisions, allisions, hull and machinery damages, and environmental damages. Therefore, this study’s purpose was to examine seafarers’ perceptions of their interpersonal conflicts on board the vessels in a multicultural workplace and to examine whether they perceive that those interpersonal conflicts may contribute to the human errors that lead to marine casualties and incidences. A two-method approach (quantitative and qualitative) was used. The theoretical framework guiding this study consisted of four theories, which were culture and interpersonal relationship conflict, social identity theory, organizational interpersonal and task conflicts theory and systems theory. The quantitative and qualitative questions that underpinned this study were used to examine the relationship between the perceptions of seafarers and the study variables: interpersonal conflicts, multinational culture, number of days of the duration of the voyage, number of national cultures onboard the vessel and the common types of conflicts and their causes among seafarers. The inferential statistics and thematic analysis of the collected data revealed that cultural differences and the number of nationalities influenced interpersonal conflicts and causalities. The results also revealed different types of conflicts that are experienced onboard the vessels. Conflicts were mainly categorized based on their main causes (e.g., conflicts related to alcohol and substance abuse).