I would like to see a Canal improvement. Where you can build a canal with workers accross a small junction of land. -It would allow ships to pass 1 hex per turn. -Perhaps limit it to 3 or 4 hexes max. -Must be within cultural borders. -May even need to be attached to a city. Or have a city within so many Hexes of all Canal Hexes. Would love to see use of the canal be attached to the diplo trading screen so you could sell access. But Open Borders would suffice if it were in the confines of cultural borders.