This is the 9520th most frequent German word.
mittelmeer
Mediterranean Sea.
Here, 'Mittelmeer' is used as a noun to specify the Mediterranean Sea, a geographical location.
Das Mittelmeer ist bekannt für sein klares Wasser.
The Mediterranean Sea is known for its clear water.
In this sentence, 'Mittelmeer' again serves as a noun denoting the location of the cruise.
Wir planen eine Kreuzfahrt im Mittelmeer.
We are planning a cruise in the Mediterranean Sea.
Here, 'Mittelmeer' is used as a noun in genitive case to describe the unique ecological system of this sea.