Um, there are no locks on the current modern Suez canal. The difference in height between the Med and the Red is only 28 feet. The resulting current is negligible and seasonal. Oops!
Wikipedia says that Senusret III specifically stopped building the canal due to the height differences. Ptolemy II later had locks built. Though this was also a canal to the Nile not the Mediterranean and so they were concerned about the salt water mixing with the lower and Nile water. Maybe navigation wasn't a concern.
https://en.wikipedia.org/wiki/Canal_of_the_Pharaohs