This is the 6290th most frequent German word.
donauinsel
Danube Island.
Here, 'Donauinsel' is used as a proper noun referring to a specific location, the Danube Island.
Die Donauinsel ist ein beliebtes Erholungsgebiet in Wien.
The Danube Island is a popular recreational area in Vienna.
In this sentence, 'Donauinsel' is again a proper noun and it is the location where the activity takes place.
Wir machen morgen ein Picknick auf der Donauinsel.
We are having a picnic on the Danube Island tomorrow.
Here, 'Donauinsel' is mentioned as the setting for the activity of cycling, emphasizing the recreational aspect of the location.