Since my last post, some readers found Google has revealed the length of the Derwent River. It gives the number of 249km without any indication of where that number was found or how it was calculated. Immediately below this information box are two listings both giving alternative conflicting distances.
My measurement of 214kms was from an arbitrary line between Cape Direction and Pearsons Point to mark the mouth of the Derwent River, and I stopped at the point where the river starts from the southern end of the Lake St Clair Lagoon.
I have noticed that one source indicates the measurement ought to be taken from the point where Lake St Clair meets the Lake St Clair Lagoon. I have found another source which seems to indicate the mouth might be where Storm Bay meets the sea. Even if the length of the Lagoon and the width of Storm Bay were added to my 214km, the Google number would not be reached. I have asked Google to identify its sources because I cannot believe their number can be accurate. Unfortunately, I have not received any feedback.
STOP PRESS – JUST DISCOVERED THE AUTHORITATIVE LENGTH IS 215KMS. Read my new November 2015 post.