Zemplinska Sirava lake. Slovakia
Zemplínska šírava (sometimes called the "Slovak sea" (Slovak: Slovenské more) is a dam and lake in eastern Slovakia, near the town of Michalovce and 30km to Slovak-Ukrainian border)
It's good for an hour trip, we stayed on the side, where swimming was forbidden, so we just were walking... there was a little park, and we tried a very tasty ice cream👌🏻😊