"On the bottom" is a common phrase that can be replaced with alternate synonyms in order to add variety and depth to your writing. Some useful synonyms for this phrase include "at the base", "lying beneath", "underneath", "lowermost", "deep down", "submerged", "fathoms below", "beneath the surface", "ground level", "base level", and "base floor". These descriptions can effectively convey the idea of something being located at the very bottom of a pile, structure, or body of water. Whether you're writing a descriptive essay, a research paper, or a novel, incorporating a variety of synonyms can greatly improve the quality of your writing.