The Pagasetic Gulf is a rounded gulf in the Magnesia regional unit that is formed by the Mount Pelion peninsula. It is connected with the Euboic Sea. The passage into the Euboic Sea is narrow and is about 4 km.
Its main port is Volos.
Wikipedia https://en.wikipedia.org/wiki/Pagasetic_Gulf
Coordinates 39°12'53.837" N 23°0'48.678" E