Hello Marney, we're staying in Kalithea in June which is on the same side of the island as you are staying, apparantely by what I've heard, Kalithea is a very good place to go snorkelling.

Mirage is right Kallithea Spa is a good spot for snorkelling, also St Pauls (Lindos) and Ladiko Bay (south of Faliraki).

Agathi Beach - right hand end facing the sea!

Kalithea is quite good. Its also the only place on Rhodes where Scuba diving is allowed (at the moment). North side of Rhodes is poor for snorkellers (windy and too open), Mediterranean side is better. Try any of the rocky bays - they should all hold some interest.