If an advanced civilization developed the technology for interstellar travel, and came all this way to earth, I suspect one of 2 things will happen. Either their tech is so advanced that we won't even detect them, or they show up ready to communicate or destroy us.
I can't see them clumsily flying around, getting seen and whooshing off like some dumb teenagers playing ding-dong-ditch.
I mean if you look at it like *observe and don't interact" then it makes a lot of sense why the craft keep going into the ocean. It's the best place on earth to hide and you can get anywhere on the planet that way.
They travel thousands of light years just to pick up some ding dong and toss him back. I just picture a grey little alien dropping off a hillbilly after a solid butt probin' with a finger over his mouth uttering, "Shhhh! No one will believe you."
Also: for a civilization advanced enough for interstellar travel to want to destroy us is unlikely. The universe is filled with resources. We pose no threat and don't really have anything special.
I don't get why everyone was always assuming 'alien' vs "time travelers."
The interest in Earth, general similarity to our own tech but more advanced, coupled with non-intervention makes a lot more sense under those conditions than aliens.