<p>The increasing use of additive manufacturing (3D printing) technologies in the maritime industry necessitates a detailed examination of the long-term durability of polymer-based parts in aggressive marine environments. In this review, the aging and degradation behaviors of common thermoplastic materials (PLA, PETG, ABS, and ASA) produced by the FDM (Fused Deposition Modeling) method under seawater exposure were comprehensively evaluated based on the literature. It was found that, unlike metallic materials that typically undergo electrochemical corrosion, polymers in marine environments are mainly affected by degradation mechanisms such as water absorption, hydrolysis, photooxidation, and salt crystallization. The studies examined show that interlayer bonding in FDM production plays a critical role in these degradation processes. Comparative analyses revealed that PLA exhibits high water absorption due to its hydrophilic structure and offers limited performance for long-term marine applications. PETG emerged as an intermediate solution with lower water absorption and more balanced mechanical properties, while ABS was reported to be susceptible to surface embrittlement under the combined effects of UV radiation and saltwater. In contrast, ASA and high-performance engineering polymers (e.g., Ultem 9085) have been found to exhibit the most stable behavior in marine environments due to their low water absorption and superior UV resistance. In conclusion, this review emphasizes the critical importance of material selection for the safe and sustainable use of 3D-printed polymer parts in marine applications and contributes to filling gaps in the literature.</p> Graphical Abstract <p></p>