Diving in the waters in and near Charleston is not like diving the Caribbean. Our waters can be murky, especially in summer and in areas closer to the coast.

And when 18-year-old James Island resident Tristen Henderson Allen disappeared Saturday at a popular diving site known as Charleston Sixty, an artificial reef located 12.5 miles from the south jetty of Charleston Harbor, the visibility was low - particularly for a diver going to the maximum depth of 60 feet.

Divers can become disoriented in low visibility dives and panic, according to local diving experts.

They also say waters along the South Carolina coast last weekend were stirred up by Hurricane Arthur and the currents caused by Saturday's "supermoon." Prior to the storm, the waters were notably clear for summer.

Tom Robinson, co-owner of Charleston Scuba and a dive master since 1983, was only three miles from the reef on Saturday when he heard and responded to the mayday distress signal. Robinson, who was leading a dive trip that day, said the visibility was around 10 feet and that the currents were very strong.

He said he arrived at the scene about 15 minutes after the distress signal and joined in an underwater search before running out of air. Afterwards, Robinson and the other divers aboard his boat continued on a "surface search."

Within 30 minutes of receiving a call, the U.S. Coast Guard dispatched the Cutter Tarpin and a helicopter to the area. The Coast Guard called off the search on Tuesday.

Dangers of diving

Robinson said that the Charleston Sixty is not a dangerous site, but that divers must be well-trained and that all safety precautions taken before diving in area waters.

Because of the variable diving conditions in Charleston, training and conditioning is even more important.

Victor Dupuis, owner of Lowcountry Scuba, agrees, saying that after basic certification, he recommends getting in 30 to 60 dives elsewhere "before making a run here." He also suggests getting an "enriched air diver," or nitrox, certification to dive longer.

By doing so, divers can justify the expense of going out to the clearer waters 30 miles offshore.

Dupuis said the two most common problems SCUBA divers face are related pressure differences in the water are "the bends" and barotrauma.

The bends, or decompression sickness, occurs in divers when dissolved gases, mainly nitrogen, come out of solution in bubbles and can affect just about any body area, including joints, lung, heart, skin and brain. Barotrauma is injury caused by changes in barometric or water pressure.

Dupuis said that the Charleston diving community is tight and that only about one or two serious incidents take place each year.

The last time someone died in a diving incident in the area was July 4, 2008, when 45-year-old electrician Tim Edwards of Mount Pleasant died. An autopsy showed that he likely died from an air or gas embolism, a condition that can happen when divers rise too quickly.

Edwards had been spearfishing with a friend 30 miles offshore when they got separated.

The star player

An outpouring of love for Allen followed as word of his disappearance spread throughout James Island this week.

He was a star linebacker on the football field and made varsity his sophomore year at James Island Charter High School, those who knew him said. He was named captain of the team his senior year and aspired to play football at The Citadel in the fall.

Allen's former coach, Randall Hilyer, was on his way to a sports camp at the University of Alabama when his phone rang about 9:30 p.m. Saturday. Allen was missing, the caller said, and the community was taking the news pretty hard.

Hilyer spent a day in Alabama then headed back to James Island to be with his players.

As a show of support, the team presented Allen's father with a jersey adorned with the number he wore so often on the field, 41.

"He was a player with a real motor and very emotional. I think that's what endeared him to a lot of the players and coaches," Hilyer said. "He'd go out there and go hard every play for you, and then do it all again next week."

The coaches at James Island always encouraged their players to think of one another as brothers, but the relationship between Allen and the other seniors on the team ran especially deep, Hilyer said.

Allen socialized with the players on and off the field. His energetic and fun-loving personality made him an easy person to like, Hilyer said.

"He had a positive effect on a lot of people" Hilyer said.

One former teammate, Jordan Bolds-Lockwood, 19, of James Island, recalled Allen hoisting him up in his arms and cheering during a graduation ceremony.

"He's a popular guy around the island. I don't think it stopped at the school," Bolds-Lockwood said. "To see him disappear like that is just unbelievable. We're not going to lose hope. We know he's all right and we're expecting him to come back. Pretty much the entire island is waiting for his return."

Friends and family members continue to search the waters where Allen disappeared off of James Island.

To help with the search or donate toward the effort, visit Allen's father's, attorney Sam Allen's, Facebook page.

Reach David Quick at 937-5516. Reach Christina Elmore at 937-5908 or at Twitter.com/celmorePC.