Red, lovely pictures of the area you live in. Sounds and looks like where you live is very similar to where I live, the island Sint Philipsland.
This is a salt marsh about 20 minutes walking from my home:
They surround most of the island, a number of them have been made into fresh water 20 years ago and are now forests with low biodiversity, many ticks and blue green algae. The governement is going to make them salt again in the coming years though.
We're not allowed on the salt ones at all, although people used to be allowed to hunt on them and gather plants like marsh samphire. Now you can only harvest the salt water plants with a permit and only in certain places.
Oh, and everything's flat here too.