This article links to another which discusses exactly that [1] — some geological event dammed the Mediterranean from the Atlantic 6 million years ago, after which the sea mostly dried out, then subsequently the entire thing refilled in the space of a couple years in the Zanclean Megaflood (at least, there’s mounting evidence that it happened in one cataclysmic event). First the western Mediterranean filled up to Sicily, then the eastern med, via a 1500m (5000ft) high waterfall!

[1]: https://everythingisamazing.substack.com/p/in-search-of-a-fl...