The word "unfathomable" is used to describe something that is difficult or impossible to understand or comprehend. When looking for antonyms for this word, one could consider phrases such as "clearly understandable," "easily comprehensible," or "simple to grasp." Other opposing terms could include "straightforward," "comprehensible," or "understandable." Each of these words emphasizes the idea that the subject in question is easily understood, and lacks the complexity or difficult nature of unfathomable subjects. With these antonyms, one can convey a sense of clarity and simplicity, highlighting the ease with which understanding can be achieved in certain situations.