Poros (Greek: Πόρος) is a small Greek island-pair in the southern part of the Saronic Gulf, at a distance about 58 km (36 mi) (31 nautical miles) south from 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.
Poros consists of two islands: Sphairia (Greek: Σφαιρία), the southern part, which is of volcanic origin, where today’s city is located, and Kalaureia (Greek: Καλαυρία), also Kalavria or Calauria (meaning ‘gentle breeze’), the northern and largest part. A bridge connects the two islands over a narrow strait.
Poros is an island with rich vegetation. Much of the northern and far eastern/western sides of the island are bushy, whereas large areas of old pine forest are found in the south and center of the island. It has a good road network and adequate tourist infrastructure, which makes it a popular resort for short holidays. Though possessing no airport, it is easily accessible from Athens via ferry or hydrofoil or from the adjacent mainland at Galatas.
In the northeastern part of the island, in a location called “Kavos Vasili”, the archaeologists have discovered the ruins of a settlement of the Early Bronze Period. This settlement is the oldest of the wider area of Trizinia, Peloponnese, and is believed to be interrelated with the wreck found on the nearby Dokos island which dates to the same period.
The ancient polis of Kalaureia was home to an asylum dedicated to Poseidon, the ruins of which are still accessible on a hilltop close to the town. This asylum may have been linked to the sanctuaries at Geraistos and Tainaros. Ancient historians claimed that Poros was home to an Amphictyony in the Archaic period, a league of the poleis Poros, Athens, Prassiai, Aegina, Epidaurus, Hermione, Troizen, Nauplion and Orchomenus. However, there is no evidence for this, and modern scholars believe the Amphictyony may have been a Hellenistic invention. An enormous feast was found dating to the Hellenistic period in the ruins of the Kalaureia asylum, along with a plaque celebrating the “revival” of the Kalaureian League.
Poros was divided in two islands during the antiquity: the one was called Sfairia and is the part of the island where today is located the island’s capital; the other was called Kalavria and is the bigger part of Poros at the north of Poros Town. During the Mycenaean dominance (1,400-1,100 B.C.) Kalavria was quite powerful as the most important naval base of the wider region was located on islet Monti or Liontari in the eastern coast of Poros. In the 7th century B.C., it is believed that Kalavria was part of an “amphictyonia”; that is an alliance between multiple City-states. The amphictyonia was named “Amphictionia of Kalavria” and its members were Athens, Poros, Aegina, Epidaurus, Hermione, Trizina, Nafplio, Orchomenos and Prasies. During the 5th century, the Persians started attacking the Greek territories along with the Aegean islands. With the beginning of the Peloponnesian War, which also affected the islands of the Argosaronic Gulf, Trizina and Kalavria offered asylum to the anti-Macedonian politician who eventually became the tyrant of the region. After the death of Alexander the Great in 323 B.C., the Ptolemies of Egypt occupied Kalavria. Around that time, the famous orator Demosthenes came to the island and some say that this is the place where he committed suicide. In 273 B.C., the last explosion of the Methana volcano dramatically changed the morphology of Poros and the wider region.