The River Lea is the river in the east of England and Greater London. It originates in Bedfordshire, in the Chiltern Hills, and flows southeast through Hertfordshire, along the Essex border and into Greater London, to meet the River Thames at Bow Creek.
It is one of the largest rivers in London and the easternmost major tributary of the Thames.
Below Hertford the river has since medieval times had alterations made to make it more navigable for boats between the Thames and eastern Hertfordshire and Essex, known as the Lee Navigation. This stimulated much industry along its banks. The navigable River Stort, the main tributary, joins it at Hoddesdon.
