High-Density Polyethylene (HDPE) sheets are a go-to material in many industries due to their strength, chemical resistance, and low moisture absorption. However, when it comes to marine environments—think boats, docks, marinas, and saltwater exposure—not all HDPE is created equal. Manufacturers often draw a clear line between standard HDPE  and marine grade HDPE (also known as marine board or branded versions like King StarBoard® or Seaboard). In this guide, we'll break down