Mystery grows about Google barges moored off US coast
Others believe they could be fitted out with new showrooms for Google Glass with a "party deck" on top.
So far Google has declined to comment on what the vessels are being used for. But the company does have a patent from 2009 for a "water-based" data centre. "It's an interesting concept," said Nick Layzell, of Telehouse, a data centre provider. "Cooling is the big cost for any data centre, so perhaps they're trying to take advantage of having some water on tap." But he added that water was the biggest threat to data centres because of the damage it could cause to equipment.
One of the barges is anchored at Pier 1, Treasure Island Marina in San Francisco.
The authority in charge of projects within San Francisco Bay confirmed that it had met with Google officials several times in recent months. Its chief executive Larry Goldzband said that Google had been "less than specific" about its plans.
"When they decide to let us know what they plan to do with it, or hope to do with it, then we can decide if it's allowable," he told AP. Documents revealed following a freedom of information request by the The Day newspaper in Connecticut show Google is also linked to a barge near Maine on the eastern coast of the United States. According to the paper, the documents did not explain what the barge would be used for but detailed a plan to "operate" the barge in different ports around the United States starting in New York.