Spooner's Boat can be easily mistaken for a waterborne vehicle with its canvas sail and boat-like appearance, but it also has four steel tyres and runs along rail tracks powered by the wind.
The extraordinary vehicle was completed in 2005 and is a replica of an original that was used as a private inspection carriage by Charles Easton Spooner, the manager and engineer of the Ffestiniog Railway in Wales about 150 years ago.
The replica has been loaned to the NRM by the Ffestiniog Railway to help celebrate the links between rail and sea as part of the museum's latest free exhibition, Once Upon a Tide.
It documents more than a century of North Sea ferry crossings between Harwich and Holland, when ferries were part of the British Railways fleet.
A roll-on roll-off ferry has taken centre stage at the NRM, enabling visitors to walk on to the deck where they can experience a unique view of the museum's turntable.