I'll start the brainstormiung.
The implosion story is a cover up and they actually entered the hollow earth through an elaborate system of locks and dams in order to meet with Peter Viereck, who has been reigning over the sub-subterranean ape people as a tyrant since 1952. Using the mystical power of orgonism they will return to the surface and subjugate humanity to build a giant crystal pyramid from which they will fight the Posada aliens. Our Orca comrades are trying to stop them by incapacitating their agents off the coast of Gibraltar.
After Epstein's first arrest, they deemed that a private island was now too obvious but still wanted to rub their hubris in the noses of the poor, so construction commenced on an Atlantean-esque bunker complex city with the entrance directly under the wreckage of the Titanic.
This was simply the first one-way trip as the first permanent residents moved in. They built the cheapest tin can possible to get them down to the entrance airlock, and after the residents disembarked they destroyed the evidence by poking a hole in its flimsy hull and dropped back out the airlock which imploded it immediately. The debris has slowly been floating up over the last week.