The Med has completely dried out (at least) 40 times, the last time was five million years ago. These guys may have walked there.
There is a 2 mile thick salt layer on the bottom of the Med with the sort of salt crystals that forms only when exposed to direct sunlight.
These guys were a few hundred thousand years too early, hence my boat suggestion — but I remembered your interest in the Messinian Salinity Crisis.
Mediterranean Sea filled in less than two years: study [Zanclean flood]
December 9, 2009
https://phys.org/news/2009-12-mediterranean-sea-years.html