True, but there's still limits to believability, and being relatively uneducated in science I don't know where that boundary lies. If it was totally unrealistic that it takes a couple of hours for the ocean to breach and fill a massive crater, then I'd work around that (for example).
You can create your own degree of believability. All the elements are fluid. Impact speed, crater depth, crater shape, proximity to ocean, ocean current or tide, is it high tide at impact or low tide, is it day/night, raining/sunshine, is the crater rim at the ocean blocked by the remains of the spaceship, is the rim simply built up earth, what's the material on the ground, is it sand, earth, gravel, rock, rubble...
I suspect the believability will lie in the writing and the readers' imagination, not the detailed science/physics.
Why not write the scene as you imagine it and then build on that after checking for possible obvious errors of logic/science.
No idea what the story is about, but are you looking to describe the event as it happens, or is it only the resulting chaos and aftermath that is experienced/witnessed by a POV character? Can't imagine who (other than an aircraft pilot) would be in a position to witness the actual event and describe it with anything other than incredulous non-scientific comments. Depending upon your time factor, the approaching craft would no doubt be detected by defence instrumentation.
Good luck.