"sea-reach of the Thames"
Map of the lower course of the Thames (1840)
Public DomainMap of the lower course of the Thames (1840) - Credit: Wikimedia Commons

The sea-reach of the Thames is that part of the Thames Estuary where the river (see Setting) meets the waters of the North Sea. Its western boundary is generally defined as being near Canvey Island on the Essex shore, with its eastern boundary running from North Foreland in Kent to Harwich in Essex.