Cumberland is a big container ship with port thrusters, which help him dock himself without any need of a tugboat. At first, the other tugs considered Cumberland to be rude and stubborn, but really he was sad because he missed his best friend Conrad Explorer. He soon became good friends with Theodore. Later on, when Emily got a new hat; he was the first to notice. There was also a time when Theodore, Foduck, Shelburne, Northumberland and George removed a sunken satellite from his path.
- Season 3 - Theodore and the Northern Lights (cameo), Theodore's Big Friend, Emily's New Hat, George and the Underwater Mystery (does not speak) and Emily's Close Call