Have to say best beaches for swimming are generally on Sithonia (Vourvourous is beautiful). However, Kassandra has more to do and villages not so spread out. Sani Beach is beautiful, sandy and shallow. The beaches around Kallithea and Kriopigi are also sandy, and safe. Personally I prefer the beaches on the other side, at Mola Kaliva (quite pebbly) and Possidi (a mix of sandy beaches and pebbly) because the sea is so clear and there are not so many people that side.
Have a great time.Sorry cannot reply in Greek, lack of Greek keyboard.
