Mirrors coat the walls, multiplying the number of sweaty, gyrating figures on the floor. A heavy beat pulses through the room, capturing veteran dancers and taunting reluctant wallflowers. Their bodies scream for water, but the lure of the next song is far too enticing.

This is Blues Underground, a biweekly social blues dance located on Capitol Hill. The venue is literally underground, tucked innocently behind a nondescript door on 15th Avenue East.

The dancing behind this door, however, is anything but nondescript.

Originating from African rhythms, partner blues dancing never entered the mainstream; the upper crust of American society found it taboo and immoral. Only recently did it re-emerge into the public eye as a derivative of the swing-dance community.

Blues Underground began as a monthly dance about five years ago, adopting a space that is also used for fitness, tango and tai chi, and has since grown increasingly attractive to Seattle’s active dance population.

“Blues has gotten a lot more popular,” said venue manager Emily Smith. “It gets so busy in here that we do it twice a month.”

The décor is simplistic and understated, lending the venue a mellow, comfortable ambiance. Tiny lights sparkle from the ceiling, casting a dim glow over the room. A coat rack and stack of chairs are available for convenience, but the main focus is, of course, the 40-foot-by-50-foot sprung hardwood dance floor.

Then, of course, there are the dancers.

To the uninformed bystander, blues dancing looks seductive and intimate, something much like two awkward and overly hormonal teenagers pressed firmly against each other, mildly swaying to a beat.

But blues dancing is far more technically advanced than what can be perceived in a cursory first glance.

When asked to define the dance, Smith fumbled for a response, pondering for a moment before replying with a chuckle.

“It’s like trying to describe salt,” she said. “Blues dancing to me is a connection. It’s not about a basic move, it’s about connecting with a partner.”

The connection is very significant, as all blues music contains a certain tension that the dancers try to mimic with their bodies.

Gina Keppel, president of the Savoy Swing Club — the group that sponsors the event — elaborated on the definition, stating that the dance is about “being able to feel how the other person is moving so you can move together in sync.”

For novices to sample the connection that is central to blues dancing, Blues Underground offers a free lesson one hour prior to each dance.

“The goal is to give them a variety of skills they can immediately apply that night,” instructor Topher Howard said of the drop-in lessons, “to give them material technically true without overloading them; [material] that’s applicable to what they face that night in terms of the music and who shows up.”

Some of the elementary skills Howard teaches include basic partnering, weight transfers and traveling. Posture and rhythmic variation are also crucial to the dance.

“From there, dancing really becomes about adding layers,” Howard said. “You can add rhythms in the legs so six or seven things are happening in the body.”

Once the basics are mastered, more complex topics are addressed.

Howard mentioned an African hip motion as one such example, where dancers learn “from a kinetics perspective what exactly the standing leg does to keep the hip up.”

While a description like that may baffle beginners, it doesn’t have to deter them from trying out the dance. Howard explained that blues dancing begins with a basic walking motion, and that’s really all that is necessary to get started. That, and perhaps a bottle of water — following a particularly heated dance, it can be tough to tell where the dampness on your shirt is coming from: you or your partner.

Experienced dancers are often on hand to assist beginners as well, offering tips and experimenting with new moves. Blues Underground caters to a diverse crowd: Beginners, experts, young and old come to surrender their bodies to the rich, somber melodies.

“The crowd is eclectic,” Smith said. “Now there’s a big age range. We get people here in their 40s and 50s, and they love it; they stay the whole time.”

UW students, in particular, maintain a strong presence at the venue.

“Blues Underground is my favorite place to blues dance because of the variety of people who attend and the welcoming atmosphere filled with smiles and hugs,” sophomore Jenny Meyen said.

Sophomore Shelly Cooper also appreciates the relaxed mood at Blues Underground.

“[There is] generally great music and fairly decent lessons most of the time,” she said. “Just a nice change of pace from other blues venues.”

Howard explained that as a disc jockey, the type of music he spins depends entirely on the evening’s crowd.

“Choosing what song to play is part of the art,” he said. “I like to choose music that pushes the dancers to dance blues instead of other styles so they improve and find new ways to express what the music is expressing.”

But blues dancing isn’t restricted to one genre of music, as the title might suggest. Older blues songs and contemporary tunes are both played. On one night, dancers might groove to the vocals of Ray Charles and B.B. King, while on another, Michael Bublé or Alicia Keys will pop up on the DJ’s set list.

If the group is made up of relatively new dancers, Howard selects songs with a steady, driving and reliable beat.

“As dancers get more experienced, I add music with more complexity,” Howard said.

Overall, the image these underground dancers create in obedience to the music is enchanting, their bodies at times suspended in the air, cheating gravity.

“Dancing creates all sorts of illusions,” Howard said. “So when we watch people dancing, we say, ‘Wow, that looks cool.’”

Reach reporter Rachel Solomon at features@dailyuw.com.