Navy officials said the old mine found floating off the shore of Bainbridge Island last week wasn’t that old, actually.

Though the wayward ordnance was earlier thought to be of World War II vintage, Navy officials said the mine that was found in the water between the island and the Kitsap Peninsula on Tuesday, Aug. 28 was really an inert training mine from an military exercise conducted in 2005 by Naval Undersea Warfare Command, Keyport.

The Navy towed the mine away from the shoreline Aug. 28 and blew it up. Because the detonation did not create a secondary explosion, it indicated the device was inert, officials said.

The Navy said the mine was detonated at 8:04 p.m. Aug. 28, and the loud explosion was heard by many across the island Tuesday night.

The mine was discovered by the Washington State Department of Natural Resources, and first appeared to have decades of marine growth on its exterior.

After the mine was discovered, the Coast Guard established a 1,500-yard water safety perimeter around the ordnance, which was drifting south about 1,200 yards east of the Brownsville Marina. A Coast Guard Station Seattle boat crew aboard a 45-foot Response Boat Medium enforced the safety zone, and the Coast Guard was joined by marine units from Bainbridge Island and Poulsbo. The Coast Guard Cutter Swordfish and Coast Guard Maritime Safety and Security Team 91101 Seattle were dispatched to the scene, along with Naval Base Bangor Explosives Ordnance Disposal Mobile Unit 11.

A 5,000-foot temporary flight restriction zone was also established in the area around the floating mine.

People living along the shoreline from Brownsville and Keyport to the Agate Pass Bridge, on both sides of the water, were told to shelter in place before the mine was detonated.

The mine was exploded without incident.

The Navy has announced it will survey the exercise areas and recover any remaining positively buoyant mines in order to avoid similar incidents in the future.