What is that thing?

The SBX drew plenty of quizzical looks as it passed along the western coast of Whidbey Island yesterday on its way to Vigor Shipyards in Seattle on Tuesday afternoon. South Whidbey residents camped out at numerous places along the coast to watch the 28-story high self-propelled mobile platform, officially called the Sea-Based X-Band Radar, make its way slowly past the island.

“It looks like the Taj Mahal on water,” quipped one onlooker as he peered through binoculars on a bluff at Scatchet Head.

The SBX was built at a cost of $1 billion and was designed to detect incoming ballistic missiles. At one point, the U.S. Missile Defense Agency had considered home-porting the massive platform at Naval Station Everett, but later decided to base the SBX in Adak, Alaska after Everett residents protested the prospect of it blocking views in Port Gardner Bay.

Similarly, the suggestion to bring the SBX to Everett for repairs last year also caused controversy from concerned residents in Snohomish County and South Whidbey. But citing a lack of pier space at the Everett Navy base, the Missile Defense Agency decided to send the platform to Todd Pacific Shipyards, now called Vigor Shipyards, for maintenance on its propulsion systems and other work that is expected to cost approximately $9.4 million.

The SBX was escorted through the Strait of Juan de Fuca and Admiralty Inlet by multiple Coast Guard vessels that enforced the 500-yard Naval Vessel Protection Zone around the platform. Boaters were kept 100 yards away from the SBX, said Coast Guard Petty Chief Robert Lanier, a spokesman for the 13th Coast Guard District office in Seattle.

Lanier said the SBX’s journey through Puget Sound attracted a lot of attention. He recalled the scene as he headed home Tuesday night to West Seattle.

“There were tons of people with cameras waiting for it to come through,” he said. “It was a pretty big monstrosity.”