An unexploded mine was seen floating in the Puget Sound in Washington state yesterday, according to the U.S. Coast Guard. With assistant from the U.S. Navy, they carried out a controlled explosion of the object last night.

The Coast Guard said a 1,500-yard safety zone was put into effect as the ordnance drifted south between Brownsville Marina and Bainbridge Island. They also implemented a 5,000-foot flight restriction zone.

The Navy inspected the moored mine and it showed decades of marine growth. Around 5 p.m., Navy divers secured a long line to the device and began towing it with a small boat. By 8:15 p.m., officials said it detonated without incident.

Brownsville is a few miles south of Naval Base Kitsap, Keyport’s torpedo testing range.