The Wentworth by the Sea is a historic grand resort hotel in New Castle, New Hampshire, United States. It is managed by Ocean Properties as "Wentworth by the Sea, A Marriott Hotel & Spa". It is one of a handful of the state's surviving Gilded Age grand hotels, and the last located on the seacoast.
Wentworth by the Sea is a member of Historic Hotel of America the official program of the National Trust for Historic Preservation.