Newhaven is a port town in the Lewes district of East Sussex, England, lying at the mouth of the River Ouse. The town developed during the Middle Ages as the nearby port of Seaford began drying up, forcing a new port to be established. A sheltered harbour was built in the mid-16th century, and a breakwater in the late 18th, to provide continued access to the sea. Newhaven increased in importance following the arrival of the railway in 1847, and regular cross-Channel ferry services to Dieppe.