|Spoiler Inside: Solution to Puzzle||SelectShow>|
British Columbia, Manitoba, Ontario, Quebec, Newfoundland and Labrador, New Brunswick, Nova Scotia, and Prince Edward Island have salt water coasts.
British Columbia and Alberta have non-straight line boundaries in the south. Other provinces also have non-straight line boundaries.
This leaves only the province of Saskatchewan. So the answer is one?
At a first look, Saskatchewan appears to be an answer, but, in fact, its east boundary has many doglegs. (Try looking at Saskatchewan’s east boundary using Google Maps with the scale showing 20 km or less.)
The answer is zero.