Hornsea is a seaside town and civil parish in the East Riding of Yorkshire, England. The settlement dates to at least the early medieval period. The town was expanded in the Victorian era with the coming of the Hull and Hornsea Railway in 1864. In the First World War the Mere was briefly the site of RNAS Hornsea Mere, a seaplane base. During the Second World War the town and beach was heavily fortified against invasion.

The East Riding of Yorkshire, often abbreviated to the East Riding or East Yorkshire, is a ceremonial county in the Yorkshire and the Humber region of England. It borders North Yorkshire to the north and west, South Yorkshire to the south-west, and Lincolnshire to the south across the Humber Estuary. The city of Kingston upon Hull is the largest settlement.