Corinth Canal in the context of Greek language

The Isthmus of Corinth (Greek: Ισθμός της Κορίνθου) is the narrow land bridge which connects the Peloponnese peninsula with the rest of the mainland of Greece, near the city of Corinth. The 6.3 km (3.9 mi) wide Isthmus was known in the ancient world as the landmark separating the Peloponnese from mainland Greece. In the first century AD the geographer Strabo noted a stele on the Isthmus of Corinth, which bore two inscriptions. One towards the East, i.e. towards Megara, reading: "Here is not Peloponnesus, but Ionia" (τάδ᾽ οὐχὶ Πελοπόννησος, ἀλλ᾽ Ἰωνία) and the one towards the West, i.e. towards the Peloponnese: "Here is Peloponnesus, not Ionia" (τάδ᾽ ἐστὶ Πελοπόννησος, οὐκ Ἰωνία); Plutarch ascribed the erection of the stele to the Attic hero Theseus, on his way to Athens.

To the west of the Isthmus is the Gulf of Corinth, and to the east the Saronic Gulf. Since 1893 the Corinth Canal has run through the isthmus, effectively making the Peloponnese an island. Today, two road bridges, two railway bridges and two submersible bridges at both ends of the canal connect the mainland side of the isthmus with the Peloponnese side. Also a military emergency bridge is located at the west end of the canal.

The Myrtoan Sea (also Mirtoan Sea and Myrtoum Mare; Greek: Μυρτώο Πέλαγος, romanized: Mirtóo Pélagos Greek pronunciation: [mirˈto.o ˈpelaɣos]) is a subdivision of the Mediterranean Sea that lies between the Cyclades and Peloponnese. It is described as the part of the Aegean Sea south of Euboea, Attica, and Argolis. Some of the water mass of the Black Sea reaches the Myrtoan Sea, via transport through the Aegean Sea (Saundry, Hogan & Baum 2011).

The Saronic Gulf, the gulf of Athens, lies between the Corinth Canal and the Myrtoan Sea.

The Gulf of Corinth or the Corinthian Gulf (Greek: Κορινθιακός Κόλπος, romanized: Korinthiakós Kólpos, Greek pronunciation: [koɾinθiaˈkos ˈkolpos]) is an inlet of the Ionian Sea, separating the Peloponnese from western mainland Greece. It is bounded in the east by the Isthmus of Corinth which includes the shipping-designed Corinth Canal and in the west by the Rion Strait which widens into the shorter Gulf of Patras (part of the Ionian Sea) and whose narrowest point has been crossed since 2004 by the Rio–Antirrio bridge. The gulf is bordered by the large administrative divisions (regional units): Aetolia-Acarnania and Phocis in the north, Boeotia in the northeast, Attica in the east, Corinthia in the southeast and south and Achaea in the southwest. The tectonic movement across the gulf is comparable to parts of Iceland and Turkey, growing by 10 mm (0.39 in) per year.

In the Middle Ages, the gulf was known as the Gulf of Lepanto (the Italian form of Naupactus).

The Saronic Gulf (Greek: Σαρωνικός κόλπος, Saronikós kólpos) 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.

The Athens urban area lies on the north coast of the Saronic Gulf.

A submersible bridge is a type of movable bridge that lowers the bridge deck below the water level to permit waterborne traffic to use the waterway. This differs from a lift bridge or table bridge, which operate by raising the roadway. Two submersible bridges exist across the Corinth Canal in Greece, one at each end, in Isthmia and Corinth. They lower the centre span to 8 metres below water level when they give way to vessels crossing the channel.

The submersible bridge's primary advantage over the similar lift bridge is that there is no structure above the shipping channel and thus no height limitation on ship traffic. This is particularly important for sailing vessels. Additionally, the lack of an above-deck structure is considered aesthetically pleasing, a similarity shared with the Chicago-style bascule bridge and the table bridge. However, the presence of the submerged bridge structure limits the draft of vessels in the waterway.

The Diolkos (Δίολκος, from the Greek dia διά, "across", and holkos ὁλκός, "portage machine") was a paved trackway near Corinth in Ancient Greece which enabled boats to be moved overland across the Isthmus of Corinth. The shortcut allowed ancient vessels to avoid the long and dangerous circumnavigation of the Peloponnese peninsula. The phrase "as fast as a Corinthian", penned by the comic playwright Aristophanes, indicates that the trackway was common knowledge and had acquired a reputation for swiftness.

The main function of the Diolkos was the transfer of goods, although in times of war it also became a preferred means of speeding up naval campaigns. The 6-to-8.5-kilometre-long (3+3⁄4 to 5+1⁄4 mi) roadway was a rudimentary form of railway, and operated from c. 600 BC until the middle of the first century AD. The Diolkos combined the two principles of the railway and the overland transport of ships, on a scale that remained unique in antiquity.

Isthmia (Greek: Ισθμία) is a Greek village and community 7.5 km (4.7 mi) southeast of Corinth. It is located in the south entry of Corinth Canal. The community spreads in the place where the Isthmian Games were held in antiquity. So, near the village important ruins of the archaeological site are kept including the Temple of Poseidon, the ancient stadium and the ancient theatre. Administratively, Isthmia belongs to Loutraki-Perachora-Agioi Theodoroi municipality and Loutraki-Perachora municipal unit.