Hafance is the name for this country used internally by Pro's writers, not by the inhabitants.
The area we're interested in is standard swamp or marshland, with much of the soil too wet for agriculture or serious building.
Silver hair - a little ethereal, at that - is standard in Hafance people. Their skin tends to be firm, flexible and rubbery and does not wrinkle or become damaged from long exposure to water. They have narrow lips and transparent nails. Their eyes are all muddy gold or goldish brown.
Hafance people have a vestigial tail, about 10cm/4" long and very thick. Their fingers and toes aren't webbed, but there is partial webbing on the thumb.
In this culture everyone has a kind of low-level connection to a 'universal' 'life force' that they call the Spirit. Spirit connection means they can sense things like gods and a person's 'life force'.
This connection is achieved through a feature of their brains, in effect like a miniature second personality (or familiar spirit or Pullmanesque 'daemon'). These have names, though they are not recognised as independent entities and the name is tacked onto the person's own name.
They do not have surnames, since they can immediately tell by (spirit-)sight if two people are related.