Look at a map where Jabal Maqla is located
How did they get across the Gulf of Aqeba?
From the Bob Cornuke account:
...There, we explored the underwater topography (bathymetry) of the Strait of Tiran, where the Gulf of Aqaba is narrowest, between the Sinai Peninsula and Saudi Arabia. And we discovered an underwater land bridge existing there today that is so problematic for shipping that two separate routes or “lanes” are designated for northbound and southbound ships to pass through. Further correlation of the Bible’s account of the route of the Exodus causes us to realize that this unusual submarine formation may well have been trod by the Hebrews themselves.