Normalised Confusion Matrix showing output from the Naïve Bayes classification test model. Suspected plastics (4) were predicted (classified) as plastics (4) by the model 86% of the time. Suspected plastics were classified as seawater (1) up to 3% of the time, or sea foam (5) 11% of the time. This suggests that some pixels were insufficiently filled with material when classified as water, or were dominated by spume or bubbles when classified as foam. The model did not classify any suspected plastics as timber or seaweed.