@ Tonnichiwa

I know Dain did something like this on his Tanaephis map (for the french RPG Bloodlust Metal). I wanted to try something similar one day but not this soon.

My problem is that I don't want the river system and the lake to be darker than the sea (obviously) and I don't know how to do it.

@GLS

Thank you for the compliment and for taking some time to give me solutions.
Maybe I'll redraw the borders of the forests so that they follow the rivers. I'll just have to move lightly some rivers and be done with it. It'll be solution 1.
For solution 2, I don't want to hide the rivers but Dain's solution might work (work is the word if you catch my drift ... BTW, the french word for work is "travail" which comes from the latin "tripalium" which is a torture device with three pikes, for impaling purposes- trivia off).

Does anyone else has ideas about this ?