The above coordinates are on the River Arun at Arundel, nearby is the Arundel Wildfowl Trust, home to many an over wintering goose. The river is tidal at this point. Arundel is a town where people who are used to the rhythm of both the seasonal and the tidal ebb and flow live. Don't go asking them about it, they won't help.
There is no other minimalist clue for this one!
Required cache co-ordinates: N50 _ _. _ _ _ W00 _ _. _ _ _
This cache is has been placed with the help of the Brambler - author of the original Wild Geese Mysteries.
You can check your answers for this puzzle on Geochecker.com.