The great lakes are large enough to not see the other shore/coast due to the curvature of the Earth and they are on an external border which makes them comparable to inland seas despite being freshwater.
The great lakes are comparabke to the Red Sea or Black Sea.
Also if I am not mistaken - aren’t there ships that go both on the Great Lakes and the open ocean? That could be a possible criterion. Most lakes don’t have ocean-going ships.
The great lakes are large enough to not see the other shore/coast due to the curvature of the Earth and they are on an external border which makes them comparable to inland seas despite being freshwater.
The great lakes are comparabke to the Red Sea or Black Sea.
Also if I am not mistaken - aren’t there ships that go both on the Great Lakes and the open ocean? That could be a possible criterion. Most lakes don’t have ocean-going ships.
That was how I was assuming the rationale went. You do see ocean going vessels on the Great Lakes.
https://en.wikipedia.org/wiki/St._Lawrence_Seaway
And I think that’s how everyone wound up with the zebra mussels. (Bilge discharge from those ships)