"It's showtime," he says. "It sounds hokey, but I'm ready to rip the door down. When we get in the cave, it's a transformation. The rest of the world is left behind. [I'm] in the zone."
Dover, 54, and his father, San, 83, are full-time tour guides at the attraction, which opened in 1930, two months before the elder Dover's birth. They are the only father-and-son duo among the 50 tour guides, who lead some 350,000 people annually through the cave to the 145-foot tall, lighted, underground waterfall.
"I love that they love Ruby Falls so much," says Hollie Baranick, tours and special projects coordinator for the attraction. "They make it their own. They take ownership of it. They're very proud of what they do. I've never seen one of them not give 100 percent."
San joined Ruby Falls first after retiring from a nearly 50-year career with IBM, Georgia Pacific and other companies that saw him and his wife move more than a dozen times. But he figures his retirement lasted all of eight days.
"My wife said, 'You really need to go to work,'" San says, "and she was not whispering. I was bored, a bother, in the way. I opened a newspaper and saw a help-wanted entry for Ruby Falls."
He came thinking he'd stay a year, he says. Instead, he has been there 13 years and has become one of the oldest tour guides the attraction has ever employed. And he says he plans on staying until his body says he can't.
Or, he adds with a wink, "until my wife grows more tolerant."
Doug, who'd worked in sales and owned a lawn care business in Marietta, Ga., for 10 years, says he needed a change in careers and geography. He toured the cave as a guest, aware it was something his father was passionate about, liked the environment and has stayed six years.
Today, he is one of Ruby Falls' most popular tour guides.
Father and son readily admit their demeanor as tour guides is different.
"Doug and I do the same job," San says, "but not in the the same way. He brings an energy very few are able to do. I go by the book."
"You wouldn't know we were father and son based on the tours," Doug says.
Baranick says both men -- who do three or four tours each day -- have their strengths. One is "just as enjoyable" as the other, she says. "We're lucky to have both of them here."
Doug tells funny stories, alters his accent and makes fun of himself, Baranick says. "He is a joy to be on tour with."
San brings in his life experience and more subtle humor, she says.
Both men, according to Baranick, are so dedicated to the attraction that they often offer suggestions on how to improve things, how to make the guest experience more pleasant.
Although San grew up in Chattanooga, he says he was like many Scenic City residents --taking Ruby Falls for granted.
"It was always there," he says. "I could go there anytime I wanted to."
Doug, on the other hand, lived in Chattanooga on several occasions as his family moved with his father's jobs. But the family was sports-oriented, and the cavern was not anything they checked out.
Once his dad started working there, Doug had to ask what Ruby Falls was. When he learned it involved an underground tour, he says, he couldn't picture his dad in a cave.
"Now," he says, "we're making up for lost time."
San believes he has taken the trip through the cavern to the falls more than 30,000 times.
"I've loved it every time I've seen it," he says. "It's the waterfall. If the waterfall were not there, I wouldn't be here. It's not just me, though. When people get to Ruby Falls, they [often] have a religious experience. They start talking about God."
Doug says the thank-yous from customers keep him coming back and from seeking work elsewhere. He says the moods and expressions of tour members change visibly within the hour-and-a-quarter tour. Typical, he says, is the child who steps off the elevator and exclaims, "Whoa!"
"I like that," he says. "I try to feed it.
"My motto is: 'It's the only fun job I've ever had.'"
The Dovers, both of whom live in Dalton, Ga., see their job as one of creating memories for those who have come to Ruby Falls. It's so important, Doug says, because people come back -- even decades later -- and never fail to mention how pleasant their previous visit was.
"It's a meaningful thing for families to come here," he says, "and we have to make it memorable."
During his tenure, Doug says, celebrities such as TV personality Rachel Ray and members of the band Led Zeppelin have come through, as well as a retired Army officer who once promised two enlisted men during Desert Storm that he would visit Ruby Falls if they made it home.
"He was shocked at the beauty of the falls," he says, "and mentioned his only regret [was] that it took him almost 20 years to make the trip and uphold the promise."
A typical visit begins with a widely diverse group of people, San says.
"Through the process," he says, "they become a tour group. They laugh together; they enjoy themselves together. It's a very bonding experience."
Today, Doug says, the people who finish the cave tour are dubbed "survivors."
"But the whole company is a survivor, he says. "It's a special place to a lot of people."
Contact staff writer Clint Cooper at email@example.com or 423-757-6497. Subscribe to his posts at Facebook.com/ClintCooperCTFP.