The Naardermeer (Lake Naarden) is one of the oldest private natural parks of the Netherlands. Amsterdam wanted to fill this area with garbage, but now it is a vital refuge for all sorts of birds. Big lakes surrounded by wetlands. If you like history, you will also find several fortresses and bunkers as part of the old defensive ring around Amsterdam. Go on a quiet day if you want to enjoy it. It is only 20 minutes by train from Amsterdam Central Station.