Environmental emergency awareness has been gaining momentum in recent years in the composite manufacturing industry, with a new generation of composite materials minimizing their harmful environmental impacts by employing more sustainable manufacturing processes and, where possible, replacing synthetic materials with more sustainable bio-based materials, thus more efficiently using energy and material resources. In this context, natural fiber composites are proposed as appealing candidates to replace or reduce the use of synthetic fibers for reinforcing polymers in several industrial fields, such as the marine sector, where composite usage has been extensively studied in recent years. This review aims to present a thorough overview of the usage of natural fiber composites for marine applications, discussing the most relevant criteria required for applications where water exposure is expected. For this purpose, the review outlines the natural fibers and matrices used, analyzes the resultant composites’ mechanical properties, and presents the fiber treatments required before manufacturing, as well as the main manufacturing processes adopted for natural fiber composite production. The advantages and disadvantages of natural fibers compared to synthetic fibers are also presented, including economic and environmental credentials. Finally, a list of marine components with natural fiber reinforcements developed in recent years is reported.