It is a boat owned by Thomas Matthews.
Maria LaGuerta is prying around former police Chief Matthews' boat when he suddenly opens a door, startling her. He clearly isn't happy to see her, since she helped orchestrate his being driven out of Miami Metro. Maria says that she believes The Bay Harbor Butcher is alive and still active in Miami. Matthews mockingly accuses her of drinking, and states, “Doakes was The Bay Harbor Butcher...end of story.”
She informs Matthews of the blood slide she found at the church, adding that bad people are still going missing, and Doakes never had a boat. Maria shows him a list of Miami personnel who still own boats. It annoys him to see his own name on it. He reminds her that he had a hernia operation at the time of the murders, which rules him out as a suspect. She inquires if any of the other names look familiar. He tells her to go home, and that she'll get no help from him, except a lift back to Cuba.
Matthews soon changes his mind and locates Maria at Ocean Promenade. He agrees to help her, if she will help him get reinstated, remarking that he is nine months shy of a 40-year pension. He complains that “boats are fucking expensive.” Maria ends up accepting his offer.
At Matthews request, Dexter appears at the Ocean Master, and finds Matthews decorating it for Christmas. After they sit down, Matthews gives Dexter the heads up that LaGuerta thinks he may be the Bay Harbor Butcher. Dexter looks astonished at the idea and asks why. Matthews reveals that Maria knows about the Shipping Yard Massacre, The Ice Truck Killer being his brother, and that the Cabin in the Everglades was rented by his mother’s killer. He bring up that both killers dismembered their victims, and thinks it’s weird.
Dexter realizes that he is being interrogated. He lies to Matthews, saying that Doakes owned a boat, but he was too fearful to tell anyone. Dexter claims that both he and Doakes had a slip at Coral Cove Marina; that’s why Dexter moved his boat. Matthews seems convinced, and promises to persuade Maria to move on.
To cover his falsehood, Dexter locates a vacant boathouse and ties it to Doakes by planting evidence inside it. After Matthews and Maria find the boathouse, Dexter returns to the Ocean Master, carrying a gift. He apologizes to Matthews for not coming forward about Doakes’ boat. Matthews reassures Dexter that he and Maria are now satisfied that Dexter is not the Bay Harbor Butcher.