Different kinds of holes, gaps and other empty spaces.
Craters are found on top of volcanoes, and they can be caused by meteors hitting the Earth. They are sometimes caused when the ground collapses above a large underground chamber like an old mine or a cave.
A dip can be one of many things. As a verb, you dip something by lowering it briefly into a liquid, for example the person in the picture is dipping some bread. The semi-liquid food he is dipping the bread into is also called a dip. Dips are very tasty, can be made from virtually anything, and are usually served with some kind of bread. Many dips are made with a yoghurt base.