The river was named the ` Riviere des Francais ' by the French Scientific Expedition in 1803 led by Nicolas Baudin . Early settlers called it the ` French River ' . The Kalgan River was named the ` Riviere des Francais ' by the French Scientific Expedition in 1803 , captained by French explorer Nicolas Baudin , in the Geographe , which anchored in what is now known as Frenchmans Bay , and was subsequently known as the ` French River ' by early settlers .