Every year, I go with my family to Greece. Seven years ago, we were in Paralia. We saw a lot of jellyfish in the sea. The jellyfish were transparent. We played with them and we had a lot of fun. Those jellyfish weren't dangerous. After a few days, they continued on their way.
The sea in Nea Kalikratia was a bit different. We saw a lot of brown jellyfish and a few purple-ish. It was very interesting. We played with those jellyfish too.