Coast Guard's Messenger is a small motor boat with a shrill whistle. He makes a speaking appearance in the episode Regatta and has a cameo appearance in the episode Sunshine. He makes a small non-speaking role in Quarantine as the mad speed boat that nearly crashes into O.J.
In Salty's Lighthouse, he and the Coast Guard are combined together to create one character named "Cappy".
The Coast Guard Messenger's whistle is similar the Coast Guard's, but with a clearer sound.