Vardar

The Vardar (; , ) or Axios () is the longest river in North Macedonia and the second longest river in Greece, in which it reaches the Aegean Sea at Thessaloniki. It is long, out of which 76 km are in Greece, and drains an area of around . The maximum depth of the river is .
Etymology.
The etymology of the word is unclear. However most probably, the origin of the name "Vardar" derives from "Vardários" from Thracian, from Proto-Indo-European (PIE) *"(s)wordo-wori-" ("black water"). It can be considered a translation or similar meaning of "Axios", which itself is Thracian for 'not-shining' from PIE *"n.-sk(e)i" (cf. Avestan "axšaēna" ("dark-coloured")). It is found in another name of the city at the mouth of the Danube, called "Axíopa" ("dark water") in Thracian, which was later translated into Slavic as "Cernavodă" (“black water”). The name "Vardários" (Βαρδάριος) was sometimes used by the Ancient Greeks in the 3rd century BC. The same name was widely used in the Byzantine era. The word may ultimately be derived from the PIE root "werǵ-", which is also the source of the English "work". 
Its Greek name, "Axios" (), is mentioned by Homer (Il. 21.141, Il. 2.849) as the home of the Paeonians allies of Troy.
Geography.
The river rises at Vrutok, a few kilometers southwest of Gostivar in North Macedonia. It passes through Gostivar, Skopje and into Veles, crosses the Greek border near Gevgelija, Polykastro and Axioupoli ("town on the Axiós"), before emptying into the Aegean Sea in Central Macedonia, west of Thessaloniki in northern Greece.
The Vardar basin comprises two-thirds of the territory of North Macedonia. The valley features fertile lands in the Polog region, around Gevgelija and in the Thessaloniki regional unit. The river is surrounded by mountains elsewhere. The superhighways Greek National Road 1 in Greece and M1 and E75 run within the valley along the river's entire length to near Skopje.
The river was very famous during the Ottoman Empire and remains so in modern-day Turkey as the inspiration for many folk songs, of which the most famous is Vardar Ovasi. It has also been depicted on the coat of arms of Skopje, which in turn is incorporated in the city's flag.
Project to construct the Danube-Vardar-Aegean Canal.
The project to construct the Danube-Morava-Vardar-Aegean Canal has been a dream for a long time. Le Figaro published a project of Athens and Belgrade on 28.08.2017. The Greek-Serbian proposal made in Beijing is Pharaonic: 651 km. A project worth 17 billion.
Vardaris wind.
The "Vardaris" or "Vardarec" is a powerful prevailing northerly ravine wind which blows across the river valley in Greece as well as in North Macedonia. At first it descends along the "canal" of the Vardar valley, usually as a breeze. When it encounters the high mountains that separate Greece from North Macedonia, it descends the other side, gathering a tremendous momentum and bringing cold conditions to the city of Thessaloniki and the Axios delta. Somewhat similar to the mistral wind of France, it occurs when atmospheric pressure over eastern Europe is higher than over the Aegean Sea, as is often the case in winter.