Parallel
Exodus 15:23
Brenton's English Septuagint · Berean Standard Bible
And they came to Merrha, and could not drink of Merrha, for it was bitter; therefore he named the name of that place, Bitterness.
And when they came to Marah (note: Marah means bitter.), they could not drink the water there because it was bitter. (That is why it was named Marah.)