The River Eden is a river in Fife in Scotland, and is one of Fife's two principal rivers, along with the Leven. It is nearly 30 miles (48 km) long and has a fall of around 300 feet (91 m). It flows from , near the border with Perth & Kinross, then slowly across the Howe of Fife (until drained in the 18th and 19th centuries a flat and waterlogged basin) and through the market town of Cupar to Guardbridge, where it enters the North Sea via the Eden Estuary, a nature reserve and an important conservation area for wading birds. The river holds a good stock of wild brown trout and hosts a fair run of sea trout and Atlantic salmon.