Hopefully a Dev sees this as I think this is a killer idea. Similar to how the map was expanded eastward to make way for the devils roar, I would like to propose that the map be expanded southward to make way for an area that contains snowy islands, glaciers, maybe even a frozen over outpost.
Other things that could go along with this are:
Finding frozen variants of treasure.
Storms would be a whiteout blizzard instead of rain.
A frosty effect on you ship.
More mountainous islands.
Foggy breathing
Frozen varieties of skeletons.
Cosmetics could range from Eskimo looking coats to an icy pirate curse
Thought I would throw the idea out there.