WEEKI WACHEE

Darrin Spivey couldn't wait to share his love of scuba diving with his son, and Dillon Sanchez was just as eager to explore the dark depths.

Sanchez, 15, got new air tanks for Christmas, so he and Spivey headed to Eagle Nest, a notoriously treacherous underwater cave complex in northwestern Hernando County.

On Christmas Day, father and son died there.

Authorities said Spivey, 35, and Sanchez, both of Brooksville, accidentally drowned. An investigation was under way Thursday to determine what went wrong.

Spivey, a Brooksville native and father of three, was a certified diver but did not have a separate certification for cave diving, according to the Hernando County Sheriff's Office. Sanchez did not have any certification.

Robert Brooks, an experienced cave diver who knew Spivey and helped recover his body, said the drownings appear to be the result of a diver who tried to go beyond what his training and experience allowed.

"The sad thing is, I told him, 'One night they're going to call me to come get you,' " Brooks said.

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Family members said Spivey and Sanchez had dived at Eagle Nest several times and respected the danger there.

"The top thing on their minds was safety," said Holly King, Spivey's fiancee. "They never pushed it. Darrin loved his family and loved his kids and wouldn't risk anything."

A roofer by trade, Spivey started diving about nine years ago. Sanchez, a freshman at Hernando High School who was enrolled in the Junior ROTC program, developed the same passion, said Sylvia Spivey, Darrin's mother. He spent hours poring over diving manuals with plans to get his certification.

"He'd found his niche," Sylvia Spivey said. "His dad would put him through drills so he'd know it like the back of his hand."

Brooks met Spivey about six months ago.

"He approached me to be his mentor, and I told him I couldn't take him caving until he got his cave card," Brooks said.

He said he loaned Spivey some equipment and urged him to take a course to get certified, but he kept putting it off.

Eagle Nest is in the Chassahowitzka Wildlife Management Area, a few miles north of Weeki Wachee Springs State Park. Below the surface of a pond is a mile of passages, one of them more than 300 feet deep. The caves are known in diving circles as the "Grand Canyon" for their stunning views, extreme depth and remote location.

Before Wednesday, at least six divers had died there since 1981, the most recent in 2009. The site was closed to divers from 1999 to 2003. A large green sign posted at the sink warns of the danger.

Spivey tried to reassure Brooks that he was staying in Eagle Nest's entrance room — a large cavern known as the Ballroom that reaches depths of about 200 feet — and not heading into the narrower tunnels. The Ballroom is still a dangerous place for a diver who hasn't had professional cave training, Brooks said.

King called the Sheriff's Office about 7:30 p.m. Wednesday. Brooks got word of the missing divers and called two other certified cave divers to help with the search.

One of the divers found Sanchez's body floating against the ceiling of the Ballroom at a depth of 67 feet. Spivey's body was found on a large mound on the Ballroom floor, at a depth of 127 feet.

Brooks said their dive computers and air gauges indicated both had descended to 233 feet and that they had run out of air — Sanchez first, apparently, because his father had deployed a long breathing hose that allowed his son to breath from his tank.

Brooks speculated that they were racing to get back to their spare "safe" tanks placed at about 130 feet and nearly made it. Spivey's body came to rest next to those tanks.

That didn't mean they would have been home free.

Because of the depth they'd reached, the pair would have needed about an hour to decompress, rising slowly enough so the air didn't form bubbles in their blood. They didn't appear to have adequate air in their tanks for that process, Brooks said.

Also, diving to that depth requires a mixture in which helium replaces some of the nitrogen in the air. That helps minimize the narcotic effect of nitrogen that gets stronger at depths beyond about 100 feet. Brooks said Spivey and his son were using simple compressed air.

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Spivey's family says it's premature to draw any conclusions until the investigation is complete.

They acknowledge that Spivey has made some mistakes in his life. In the late 1990s, he was convicted of lewd and lascivious behavior on a child. The girl was 14, Spivey was four years older, and the sex was consensual, Sylvia Spivey said. The girl got pregnant and had Sanchez. Spivey was required to register as a sexual offender.

In 2010, he pleaded guilty to leaving the scene of a wreck involving death after he hit a bicyclist with his truck in Brooksville. He served two years in prison and was released in October 2012.

Despite these setbacks, Spivey raised Sanchez and was a good father to his other children, Alexis, 16, and Derek, 8, his family said.

"He's made some bad choices," Sylvia Spivey said, "but he didn't run from his responsibilities as a dad."

Brooks said it was clear Spivey had taken great care in setting up the equipment they had on hand Wednesday, but their lack of experience and proper gear in a place like Eagle Nest proved fatal.

"They were pretty much doomed from the start," he said.

News researcher Natalie Watson contributed to this report, which includes information from Times files. Tony Marrero can be reached at tmarrero@tampabay.com or (352) 848-1431. Follow him on Twitter @tmarrerotimes.