Poros is a small Greek island-pair in the southern part of the Saronic Gulf, about 58 km south of the port of Piraeus and separated from the Peloponnese by a 200 m (656 ft) wide sea channel, with the town of Galatas on the mainland across the strait. Its surface area is about 31 square kilometres (12 sq mi) and it has 3,261 inhabitants (2021). The ancient name of Poros was Pogon. Like other ports in the Saronic, it is a popular weekend destination for Athenian travellers.

The Saronic Gulf or Gulf of Aegina in Greece is formed between the peninsulas of Attica and Argolis and forms part of the Aegean Sea. It defines the eastern side of the isthmus of Corinth, being the eastern terminus of the Corinth Canal, which cuts across the isthmus. The Saronic Islands in the gulf have played a pivotal role in the history of Greece, with the largest, Salamis being the location of a significant naval battle in the Greco-Persian wars. The Megara Gulf makes up the northern end of the Saronic Gulf.