Quote Originally Posted by D-Type View Post
Where does a river finish and the sea begin? Taking a well-known example, does the Thames end at Gravesend or Southend? There must be some sort of geographers' agreement.
Southend - or to be precise Shoeburyness; which sounds to me like an adjective.

A river ends at the imaginary line where it meets the sea. In the case of the Amazon, that line is more than 300km across.