SILVERDALE, Wash. -- A 'military mine' found floating Tuesday near the Brownsville Marina has been determined to be part of a Naval training exercise conducted 13 years ago.
The Navy said Thursday, the inert mine was from an exercise called, "Naval Undersea Warfare Command" conducted in 2005.
The exercise was an opportunity for academia to demonstrate various unmanned underwater vehicles and their capability to detect underwater objects and avoid submerged obstacles.
During the exercise, inert training mines were placed in areas between Brownsville, Keyport and Bainbridge Island.
According to the Navy, only a small number of the training mines were positively buoyant and not all were recovered.
The mine discovered on Tuesday was positively buoyant.
To avoid similar incidents in the future, the Navy said they will survey the exercise areas and recover any remaining positively buoyant mines.
On Aug. 28, a "dated military mine" was found in waters east of the Brownsville Marina.
The U.S. Coast Guard set up a 1,500-yard safety zone around the device and asked people in the surrounding area to shelter in place.
Several hours later, the Navy inspected the device and towed it to a safe area before detonating the mine.
"Upon initial inspection, the unidentified moored mine was found to have decades of marine growth," the Navy said.