A friend took me to Secovlje Salina on Slovenian coast.
They still make lots of salt here and have a nice museum and walking paths, where you can watch autochthonous species of birds, some of them really nice looking.
You need a few hours if you want to see the whole Salina, because it’s pretty big but it’s worth the couple of euros.
You can check the site at: www.soline.si