Newhaven lies at the mouth of the River Ouse, in the valley the river has cut through the South Downs. Over the centuries the river has migrated between Newhaven and Seaford in response to the growth and decay of a shingle spit (shoal) at its mouth.
There are two train stations in Newhaven; 1 Newhaven Town and 1 Newhaven Harbour. Counterintuitively, you should get off at the Newhaven Town station for the port – not Newhaven Harbour. There is only about a two minute journey between the two stations and they’re both on the same line, so there’s no problem if you miss the station you were meant to get off at. You can get to Newhaven easily with direct trains from Lewes and Brighton. You can also, with changes, get there from Eastbourne via Lewes, Gatwick Airport via Brighton, Portsmouth and Southsea station via Brighton and London Victoria via Lewes as well.