That's pretty much a given. But what about the debris patterns? For example at Metor Crater I understand they've found ejecta, fused material that remained in the crater and close by. If it had been underwater, would small material remain on site between the effects of the strike itself and the in rush of water that filled the location only moments later?
Tsunamis won't be much of a threat to most vessels as long as it wasn't near shallow water or a land mass and since the Flood myth imagines water covering the highest mountains, most of the earth would have about five miles of water under the hull.
Of course, that has little to do with this thread.