Question

The huge hole left by the collapse of a volcanic mountain is called a?

Answer 1

The name for such a hole is "caldera" which is a word of Spanish origin meaning "a pot" or a "cooking pot" (thing of cauldron!) - and this word is used because it resembles the shape of this hole.

Often the Calderas are filled with water forming lakes and often there is an island in the middle of the water.