Google did not respond to multiple requests for comment. But after going through lease agreements, tracking a contact tied to the project on LinkedIn, talking to locals on Treasure Island, and consulting with experts, it's all but certain that Google is the entity that is building the massive structure that's in plain sight, but behind tight security.

Could the structure be a sea-faring data center? One expert who was shown pictures of the structure thinks so, especially because being on a barge provides easy access to a source of cooling, as well as an inexpensive source of power -- the sea. And even more tellingly, Google was granted a patent in 2009 for a floating data center, and putting data centers inside shipping containers is already a well-established practice.

This. Is. So. Cool.