With this modcomp you can add a third type of water terrain to your game. I use it for my medieval sailing ships, these can sail on ocean, but not on deep sea. Tu use it, fill in all xml files in the existing xml of your mod and add the python part to the existing CvEventManager.py.
I requested it, LittlePritt made the basic code of the python-program, and The_J helped me to find all mistakes of this code.
deep ocean (Python & xml) 2016-10-05
deep ocean (Python & xml)