The River Esk is a river in North Yorkshire, England that empties into the North Sea at Whitby after a course of around 28 miles (45 km) through its valley of Eskdale. The river's name is derived from the Brythonic word "isca" meaning "water". The Esk is the only major river in Yorkshire that flows directly into the North Sea; all other watercourses defined as being major rivers by the Environment Agency, either flow to the North Sea via the River Tees or the Humber Estuary.

North Yorkshire is a ceremonial county in the Yorkshire and the Humber and North East regions of England. It borders County Durham to the north, the North Sea to the east, the East Riding of Yorkshire to the south-east, South Yorkshire to the south, West Yorkshire to the south-west, and Cumbria and Lancashire to the west. Northallerton is the county town.