If you research "pretty seaside towns in Greece", Nafplio often pops up on the search.
Located in the eastern Peloponnese, Nafplio boasts narrow, bougainvillea-covered streets, rich-hued neoclassical mansions, wrought-iron balconies and cobblestone and marble streets. It is a popular weekend resort for Athenians due to its waterfront cafes and restaurants, fresh seafood, and pretty boutiques. It is also the perfect base to explore all nearby ancient ruins such as Mycenae, Epidaurus, and Sparta.
Sip a cold drink in Syntagma Square, the town center; climb 999 rock steps up the Palamidi Castle for the expansive view; swim in the clear blue waters of the local beaches; and take a sunset stroll along the marina waterfront before dinner.