A 528-foot dry dock on its way to Mexico from Seattle sank early Wednesday morning about 40 miles west of San Francisco, U.S. Coast Guard officials said.
The crew of the 111-foot tugboat Ocean Ranger was towing the dry dock when they realized it was taking on water and called the Coast Guard.
Dry docks are narrow basins or vessels that can hold water and be drained after a boat is floated in for work such as repairs.
Coast Guard officials began an hourly communication with the crew of the Ocean Ranger to monitor the dock’s status. Coast Guard officials also sent a helicopter to assess the situation.
The helicopter crew confirmed the dry dock was listing.
The Ocean Ranger was traveling west, but eventually had to release the dock, Coast Guard officials said. It sank at about 2 a.m. in about 3,000 feet of water.
A Coast Guard helicopter was unable to find the dry dock Wednesday morning.
Fuel and hazardous materials were removed from the dock before it left Seattle and no one was injured.
Coast Guard officials said they have notified the California Department of Fish and Wildlife’s Office of Spill Prevention and Response, the Governor’s Office of Emergency Services and the Monterey Bay National Marine Sanctuary.
Why the dock sank is under investigation, according to Coast Guard officials.