The US Navy is interested in learning about the degradation properties of 3D printed polymers for waterborne environments for a broad range of uses, especially for unmanned underwater vehicles (UUVs). The ability to print parts quickly and easily would be beneficial for research prototyping, a reduction in the need to carry spare parts, and weight savings. The goal of this project is to find a 3D printable material with high mechanical properties and UV resistance, as well as a coating that prevents significant degradation of mechanical properties during exposure to seawater. Mechanical test samples were printed from thermoplastic polyurethane 92-A and acrylonitrile styrene acrylate filaments. A subset of the samples was then coated with XTC-3D and XTC-3D mixed with UVO colorant to mitigate degradation in seawater. This degradation behavior was examined with immersion tests of samples in seawater for cycles of three days, followed by tensile testing and Charpy impact testing. If the yield strength and impact toughness of the materials do not decrease more than 10 % after completion of the immersion tests over as-printed control samples the project will be considered successful. In addition to the seawater exposure, all materials used must be able to withstand expected operating temperatures ranging from 10°F - 140°F.