Numbers 33:8

And they departed from before Pihahiroth
Being forced by Pharaoh's army pressing upon them:

and passed through the midst of the sea;
from shore to shore, as on dry laud:

into the wilderness:
that part of it which lay on the other side, for still it was the wilderness of Etham they went into, as follows:

and went three days' journey in the wilderness of Etham, and pitched in
Marah;
so called from the bitterness of the waters there, and which is computed to be forty miles from Pihahiroth.