The divers take the hard drive. The technology bears a striking resemblance to computers found around the world, except more advanced, enforcing the possibility that this thing is human in origin.
Another diver looks around and finds a picture of a child and woman drilled to a desk. Both human, so more proof. The background of the image appears to be metallic.
They stumble upon what appears to be an operations center or control area or something. Th-
Transmission cut off. Squares of the steel hull of the thing kinda slide away to reveal some rocket thrusters, which pull out and aim down. This is only enough thrust for the sphere to lift itself out of the water and float against gravity. Water, what little there was, is seen pouring out of the open hatch. The divers and other debris are scattered on the surface of the water. The divers appear to have died, most likely from hitting the walls and the debris when they were being drained out of the sphere.
A large round thruster thing starts revealing itself at the bottom of the sphere. It is then seen starting to glow then the sphere... disappears.
Hours later a radio message is beamed - from the moon - to all known superiors of nations/organizations.
"No doubt you have heard of a strange thing that happened at your ocean a little while ago. I'd like to make it clear that we never intended any harm or discomfort in your people. We gave up hope for humanity on earth, but now we know that humanity is still thriving and ever flurishing
Here is our explanation for what you have seen these past years. Back in the 1980s the United States of America set out to do an ambitious project. They aimed to build a self-sustaining base on the moon. They succeeded in doing so, and kept it a secret for reasons unknown to us. The original crew consisted of one hundred brave men and women. Today, there are well more than four hundred. We have managed two generations of scientific discovery and exploration.
We wish to return to the human race. Share our knowledge with the world. Please, take interest, and we will reveal everything to you."
The message ends.