[thatjoeoverthr]

Regarding oceans, I want to add that the overwhelming majority of our land is in the northern hemisphere. Add the speed of light time lag, and anyone starting with a southern perspective will see a water-world with no technosignature whatsoever.

If one were to send a probe, one could wisely plan on purpose to land it in the ocean, deploy submersibles with flight technology and have them just go around and lay low.

They would hide, lay low and their aerodynamic performance might simply be their idea of a modest, basic platform. They would otherwise be wholly unprepared to make contact or perform in air to air combat.