The Myraham is a merchant ship.
The ship transports Theon Greyjoy from Seagard in the Riverlands to Lordsport on Pyke. Theon has a brief affair with the captain's daughter while onboard.
In the books
In the A Song of Ice and Fire novels, the Myraham is a fat-bellied trading galley from Oldtown.
In the third novel, the captain of the Myraham tells the Starks about Balon Greyjoy's death.