Canals mechanics

[Rever 1]

I have an idea that consist about a mechanic for the canals like the instanbul, panama and Suez canals for navy passages (if there's gonna be a navy)

This consist of:

whoever control these zones can be payed  for passages to access in other seas(Black Sea, Red Sea) except for the allies of that nation.

Plus the possibility to block the passage from a nation or the canal itself and add in the ultimatum list "grant access to the canal" or something like this.

I don't know how far this idea will go but I'll hope this may be useful in something else. 

[BIGCHUNGUS 9]

I need this

[Barbaris 115]

This is a great idea! 
I also propose to add significant economic growth of the population (+20, +15) in the province with the strait (for example, this is a trade route, so development is faster than anywhere else). Since historically there has been a struggle for canals (for example, for the Bosphorus), this mechanics will make provinces with canals strategically important. 
I also suggest adding the Bab el Mandeb Strait (this is the outlet from the Red Sea to the Indian Ocean), strait of gibraltar and the Ehresund (between Denmark and Sweden)

Edited January 19 by Barbaris
I wanted to add the Strait of Gibraltar