How badly does Google want to keep under wraps a mysterious project taking shape on a barge in San Francisco Bay? Badly enough to require some US government officials to sign confidentiality agreements.
At least one coastguard employee has had to sign a non-disclosure agreement with the internet giant, said Barry Bena, a US coastguard spokesman. Another person who would only identify himself as an inspector for a California government agency had to do the same.
Moored in the shadow of the Bay Bridge off Treasure Island, a former military base, the nondescript barge is stacked several storeys high with white shipping containers, and sprouts what appear to be antennas on top. The hulking structure, half shrouded in scaffolding, has stirred intense speculation in the Bay Area since reports of its existence surfaced late last week.
Technology website CNET theorised it might be a floating data centre that would house banks of computers. Local TV station KPIX said the barge was intended to serve as a floating retail store for Google's "Glass" wearable computer device.
Adding to the mystery, a second similar barge was recently spotted in Portland, in the US state of Maine. Both are reported to be registered to the same firm, By and Large. The company refused even to acknowledge its affiliation with the vessels.
Secrecy is a standard business practice in Silicon Valley, where technology companies such as Apple go to great lengths to keep their latest gadgets under wraps and a constellation of blogs compete to reveal highly prized details. But the concealment effort surrounding the barge is in another league. Chain-link fences and security guards encircle a pier and a couple of nearby buildings on the island, which sits between the cities of San Francisco and Oakland.
A California state inspector said he had to surrender his mobile phone and sign a confidentiality agreement in order to enter.
Bob Jessup, a construction company superintendent who works in a building across the street, said Google had spent the past year working on the project.
He said they fenced off a wide area and brought in at least 40 welders a day, who worked around the clock and refused to say a word.
"They wouldn't give up any of the information. It was a phenomenal production. None of them would tell us anything."
He said they worked on the inside and the outside of the shipping containers, outfitting them with electronics - "very hush hush" - and then loaded them onto the barge with a crane.
Larry Goldzband, executive director of the San Francisco Bay Conservation and Development Commission, said his agency had had several meetings with Google officials about the barge in recent months. Yet the company provided little information other than telling him that the vessel would be used for "general technology purposes", he said.
Google "could not give us a specific plan of any kind", Goldzband said.