U.S. Navy experts detonated one unexploded ordnance underwater at Kaneohe Bay this morning, and disposed of the other one, which is unarmed, at another site.

The state Department of Land and Natural Resources on Wednesday warned ocean users to stay away from the Sampan Channel area of the bay while crews took care of the munition.

The blast sent a column of water about 40 feet into the air, the DLNR in a news release today, detonating what was believed to be a munition that was at least 50 years old. A 2,100-foot circular perimeter was maintained for safety.

The so-called “Operation Kaneohe Bay Response” by the Navy’s Mobile Diving and Salvage Unit One Detachment Explosive Ordnance Disposal took place because the munition’s armed fuses made it dangerous, the department said. The DLNR made a request to have the ordnance removed.

“The Sampan channel is an important area for fishing, boating, and diving,” DAR Administrator Brian Neilson said in a statement. “We are glad that the Navy EOD was able to successfully remove these hazards from the area so these activities can safely continue.“

The second unexploded ordnance, about 1,000 pounds, was corroded and had “extensive marine life” on it. The Navy team brought it to the surface, and it was towed to shore, placed on a flatbed truck and disposed of elsewhere.

Hi‘ilei Kawelo, the director of the nearby Peipei Fishpond who found the ordnance while fishing, said she wasn’t surprised that they were there.

“As 8th generation residents of the Kahaluʻu and Kaʻalaea ahupuaʻa and fishers of Kāne’ohe Bay, we know full well the extensive military history in the area,” Kawelo told the DLNR. “So, it’s not surprising that old military munitions and (unexploded ordnance) exist on land and in the waters here. We were surprised however by the size of the munitions, measuring 4 feet in length, as well as their location, in the Sampan channel. Knowing the channel and the large amount of boat traffic and fishers that use the area, we thought it was important to bring the matter to the attention of DLNR as it’s a major safety concern.”

The department said initial surveys showed no harm to marine wildlife. A DLNR Division of Aquatic Resources biologist on a boat scanned the water to ensure that wildlife such as turtles were out of the area.