The plain of Megalochori is famous for its vineyards. The harvesting is the best time. The roofs of the houses covered with grapes, to be sun-dried in order to make raisins the sweet wine of Santorini.
For swimming you can go to the southern beaches like the Vlychada beach impressive with a marina that host tourist and fishing boats. Megalochori is a good place to stay because its not far from Fira and near to nice beaches and the site of Akrotiri.