Poros is a small island separated by a strait of just 200 meters from the shore of the Peloponnese. In the antiquity, the island hosted an asylum dedicated to Poseidon the god of sea, and was a naval base of the region. In modern times the first naval base of Greece was established there after independence in the 19th century.

The town of Poros is built on the slopes of a hill and is nowadays a popular summer resort.