They set out from the Red Sea and camped in the Desert of Sin.

Exodus 16:1
On the fifteenth day of the second month after they had left the land of Egypt, the whole congregation of Israel set out from Elim and came to the Desert of Sin, which is between Elim and Sinai.

Numbers 33:10
They set out from Elim and camped by the Red Sea.

Numbers 33:12
They set out from the Desert of Sin and camped at Dophkah.

And they removed from the Red sea, and encamped in the wilderness of Sin.