The silurian hypothesis is about another smart civilization on earth.
the crust surface under the sea is tectonically recycles more often then land crust
cetaceans as whole returned to the ocean somewhere like 50 million years ago
So there we have it. It’s a bunch of species of futuristic super smart water mammals or whatever they evolved into.
okay then… “Smart” whales that evolved 50 million years ago with language abilities and are now responsible for the UAP sighting we see around the world.
With your extra information it seems even more reasonable that during this time some cetacean with comparable to human or higher language abilities evolved.
So far we have a limited understanding of the undersea world and any whale or dolphin descendant that can create what is seen is certainly able to keep themselves hidden if they wanted to.
No one said anything about whales coming from space though…? Not sure where you got that notion. The idea that a branch on the tree of life is suddenly from another world seems ridiclious don’t you think?