Under Paris has a seemingly unrealistic premise, but it bears a striking resemblance to a real-world event from 108 years ago that was rumored to have inspired Jaws. Under Paris depicts a group of sharks moving from the Atlantic Ocean into the Seine in France, just in time for a triathlon to take place in the river. There aren’t really sharks in the Seine, though, and there are quite a few reasons they wouldn’t be able to make it that far inland, which makes Under Paris seem impossible. There was, however, a real-world tragedy in 1916 that makes it less unbelievable.

https://screenrant.com/under-paris-real-shark-attacks-jaws-inspiration-reminder/