The River Medina is the main river of the Isle of Wight, England, rising at St Catherine's Down near Chale, and flowing northwards through the county town Newport, towards the Solent at Cowes. The river is a navigable tidal estuary from Newport northwards, where it takes the form of a ria. This occurred because the Medina used to be a tributary of what was once the "River Solent", with a larger catchment area. As the Solent valley flooded, the river received less water and more sediment, causing it to become more tidal.