Caminha is the last town in Portugal, from here it is a 1.7 swim or a quick water-taxi across the estuary. The service is offered by xacobeotransfer.com, which is also where you can find their schedule (though it is also posted in every accommodation in Caminha).
It is here that the Atlantic meets the Río Miño, making for the ideal natural boundary. The main square (Praça Conselheiro Silva Torres) makes for the perfect place to rest the afternoon or while away the evening. At its northern edge stands the Torre do Relogio, where a euro affords you access to the best view in town. Further north, and adjacent to the old defensive walls, is the Igreja Matriz de Caminha.
At the far end of town the road meets a roundabout and crosses a smaller river by way of a bridge. DO NOT CROSS THE BRIDGE unless Valença or Tui is your destination. Arrows here still exist, and if they do they are pointing the way to Tui along the Central Way. Instead, turn back towards the harbor; signed "Ferry Boat".