The Navy has identified two Virginia Beach-based divers who died Tuesday during an underwater operation in Maryland.
Petty Officer 1st Class James Reyher, 28, and Petty Officer 2nd Class Ryan Harris, 23, died during a planned dive at an Army base in Aberdeen, about 40 miles north of Baltimore.
The divers belonged to Mobile Diving and Salvage Unit 2, part of Explosive Ordnance Disposal Group 2 at Joint Expeditionary Base Little Creek, said Lt. Nathan Potter, a spokesman for the command.
"Ryan and James epitomized the unsung hero persona of the Navy diver," said Cmdr. Michael Runkle, their unit commander. "We are fortunate to have had the opportunity to serve with them."
The Navy is investigating the incident but has released few details. Former Navy divers said it's obvious that something went very wrong at Aberdeen Proving Ground.
Austin Fall, a retired lieutenant commander and diver with 24 years' experience, said the Navy trains its divers to plan for every scenario.
Fatal accidents involving even one Navy diver are rare, Fall said. "I've never heard of two guys at the same time."
Still, diving is inherently risky, he said.
"Typically, you are not diving in Caribbean waters where you can see clearly," Fall said. "Anything north of Florida this time of year is cold; it's dark. Everything you do is in the dark. If there is a malfunction, you have to try to correct it by feel, and because it's cold, it's like you're doing all of this while wearing thick mittens."
Reyher and Harris were diving at an underwater testing facility at Aberdeen Proving Ground. The spot is known as the Super Pond -- a 1,070-foot-long, 150-foot-deep pond on the banks of the Bush River that's used to shock-test ships and submarines.
Emergency workers were called to the pond around 2:30 p.m. Tuesday, base spokesman Kelly Luster said. They found one of the divers dead; the other was taken to a hospital and pronounced dead.
The sailors' deaths mark the second fatal incident at the pond in as many months. In January, a civilian engineering technician died during a maintenance operation at the underwater test facility. Afterward, the facility commander ordered a "safety stand down" to allow personnel time to review operating procedures.
Officials have not said what the purpose of Tuesday's dive was.
Rob Rice, a former Navy diver and owner of Dockside Diving in Virginia Beach, said that Navy divers often wear a "hard hat" or helmet when diving in an area where there is construction or ships.
The divers will breathe inside the helmet like in a space suit, with air pumped in either from a tank on the diver's back or, more often, an air source above the water's surface.
Rice was a submariner and certified diver who joined the reserves in 2002. He helped with minor salvage and diving operations while attached to Mobile Diving Salvage Unit 2.
He said the Navy has precautions in place to prevent accidents, including checks and double checks of air flow, air and gas mixtures and communications systems. The protocol is to pull divers up immediately if communications fail, and backup divers should be on the scene in case of trouble.
"The Navy diving I was trained in is probably the safest diving in the world," Rice said. "We went through very stringent training."
Harris, a native of Gladstone, Mo., enlisted in the Navy in June 2007. Reyher, of Caldwell, Ohio, joined in May 2008. Both passed through the Navy's rigorous diving school and were designated as Navy divers within a year of enlisting.
In January 2012, another Little Creek-based diver died during a training exercise off the North Carolina coast. Petty Officer 2nd Class Taylor Gallant was assigned to Explosive Ordnance Disposal Mobile Unit 12.
In December 2011, a Chesapeake police officer, Timothy Schock, died during a dive training exercise in Oak Grove Lake Park. An investigation found that two pieces of his equipment failed, and no boat was on hand when he failed to surface.