Origin of the Term. A depth charge is an explosive device used by the military against submarines and other underwater targets to detonate at a certain level. The charge is ready to explode as it goes further down within the sea or ocean.. Create an Explosion in Your Writing. Pick the most interesting or important words in a sentence.Write another sentence or phrase related to the word(s). The elaboration should still flow with the ideas but create more detail.Depth charge more layers to create a bigger explosion..