And when they came to Marah, they could not drink of the waters of Marah, for they were bitter: therefore the name of it was called Marah. Marah - So called from the bitter waters found there. Dr. Shaw conjectures that this place is the same as that now called Corondel, where there is still a small rill which, if not diluted with dews or rain, continues brackish. See his account at the end of Exodus (Exodus 40:38 (note)).
Related Commentaries of Exodus 15:23
Exodus 15:23
23 And when they came to Marah,b they could not drink of the waters of Marah, for they were bitter: therefore the name of it was called Marah.