Poros is a small island pair in the southern region of the Saronic Gult. It includes two islands, both Sphairia and Kalaureia, which are connected by a bridge over a narrow isthmus. The Poros municipality also includes part of the mainland, Kyani Akti, at the most eastern point of the Peloponnese peninsula.

The town of Poros is a beautiful and picturesque place with neoclassical buildings built amphitheatrically on the slopes of a hill. The clock tower, built in 1927, is its most famous landmark. The Archaeological Museum at the Korizis Square holds items from the Sanctuary of Poseidon, as well as other pieces from sites nearby. On the northern section of the island are the remains of the Sanctuary of Poseidon, estimated to have been constructed in 520 BC.
Poros is also home to the Hellenic Naval Academy, which was the site of the first naval shipyard in modern Greece, and was established during the Greek War of Independence from the Ottoman Empire in 1827.

Poros is often used as a base for visiting the nearby attractions on the mainland, including Epidaurus, and the lemon groves of Limonodassos.