Question

why is europe considered as a peninusla

Answer 1

Europe is sometimes called a "peninsula of peninsulas", to draw attention to the fact that Europe is a relatively small, elongated appendage to Asia, and that a large part of Europe is made up ofpeninsulas.

Answer 2

The continents of Europe and Asia form the Eurasian landmass. The continent of Europe sticks out from the western end of this landmass. It looks like a giant peninsula. Inside Europe are other peninsulas  which all goes to explain how Europe got its nickname - the peninsula of peninsulas