Tidmouth is a town situated on the River Tid Estuary, on Sodor's west coast. With a population of 35,000, it is the largest town on Sodor. It is home to the headquarters of the North Western Railway and the main line sheds.
The Tidmouth, Knapford and Elsbridge Light Railway reached the town via a road-side tramway from Knapford, which was destroyed after a gale in the autumn of 1908. A treasury grant was obtained in 1910 and a tunnel was built. In 1916 the North Western Railway completed another tunnel, this time with an extra line, and Tidmouth's value as a harbour began to be used.
The passenger station has four lines and a "through" road (leading to the Arlesburgh branch line), sheltered by a glass roof.
The local economy mainly comes from ship-building, fishing and heavy industry.
The town's motto is "Industry and Progress".