Enclosed seas, such as the Mediterranean and Red Seas, can be very salty indeed. This is because the removal of fresh water by evaporation is much larger than the addition by rainfall, and lower-salinity waters from the deep sea can’t flow in as easily.
Is this dead sea?
It is not dead but ages ago, a saltwater lagoon was connected to the Mediterranean Sea. The movement of the African and Arabian tectonic plates shifted the land between the Dead Sea and the Mediterranean rose.