ORIGINAL: Andrew Brown
ORIGINAL: Kull
From the same AAR (two posts down), he mentions the river between Diamond Harbor and Calcutta. And indeed the F6 key confirms it, but the waterway is not visible on the map.
From memory that is deliberate. It is a navigable river hexside that allows ships to move directly between Diamond Harbour and Calcutta, without having to transit through hex 51,37. I think there were a couple of other spots on the map where I did something similar.
I agree the river should be there, it's just invisible on the map, and only the F6 key tells you it's there. Just suggesting a fix to the graphics, not the underlying code.