As remote sensing is becoming more integral in future plastic litter monitoring strategies, there is need to improve our understanding of the optical properties of plastics. We present spectral reflectance data (350–2500 nm) of wet and dry marine-harvested (Atlantic and Pacific oceans), washed-ashore, and virgin plastics. Absorption features were identified at ~ 931, 1215, 1417 and 1732 nm in both the marine-harvested and washed-ashore plastics.