(CNN) Jumping into a pool of women and men wearing fish tails is like being in an aquarium where characters from a familiar Walt Disney movie have come to life.

The multicolored fins bedazzle the startled swimmer with their sparkles and their synthetic scales light up the chlorinated water. The mermaids, mermen and merchildren look at ease free diving up to 15 feet deep, their eyes wide open and their mouths fixed into effortless toothy-smiles. But what looks easy to these "merfolk," has actually taken a lot of time, practice and money.

"The breath hold is extremely challenging," Hannah Fraser, explains, "It's a mind game, your mind is telling you, you need oxygen. You just have to stay calm."

In her 13 years working as a mermaid, Fraser, known professionally as Hannah Mermaid , has learned to double her capacity to hold her breath underwater, going without an inhalation for up to three minutes.

Fraser is one of the 200 mermaids, mermen and merchildren attending NC Mermania at the Greensboro Aquatic Center in North Carolina. Fraser works mainly in what she describes as "eco-art activism," appearing in videos around the world, swimming tail-clad at times with real fish ranging from tiger sharks to humpback whales to manta rays

Shannon Rauch, or Mermaid Shannon , became involved in the community as an alternative form of exercise. Before she knew it, people started paying her to show up at birthday parties in tail. Once she realized she could start making money off her new hobby, she left her job as a broadcast journalist, got trained in CPR and started teaching swimming classes to kids. She now makes $250 for a two-hour appearance.

Rauch's favorite part of her job is bringing fantasy to life:

"I love the magic on a child's face when there's something that's supposed to be a myth sitting right in front of them."

The emergence of the professional merfolk community can be dated back to the mid-20th century. One of the first places with a live mermaid show was Weeki Wachee Springs in Florida, which began in 1947.

Marla Spellenberg was a mermaid there from 1969 to 1972. She would put on three 45-minute underwater shows a day of "Cinderella" featuring a fairy god mermaid and "Mermaids on the Moon."

Spellenberg finds it incredible how far the mer-community has come since she first started, but she worries about the safety of those who get involved too quickly:

"People want to 'tail swim' immediately without taking baby steps, but you have to have the right training, first."

Spellenberg came to NC Mermania with her husband, who calls himself "Mertender Steve." He helps transport the mermaids by wheelchair or dolly when they need to go from one place to another via land.

"Sometimes I also call myself an enabler; some of these kids have more interest than they have money," he says jokingly.

Purchasing a mermaid tail can cost anywhere from $10 for a lightweight fabric tail to upwards of $3,500 for heavier silicone ones . Many of the mermaids make their own tails and often begin selling those to others.

Kariel JoAllen, or Mermaid Kariel, started her own business selling her homemade " Tails of Art ." She hand stitches and custom molds her tails for her customers. It takes four months for her to make each one. The cost: $2,900 and up. The mermaids compare these intricate tails to waterproof "couture gowns." The high-quality tails often weigh over 50 pounds and because they are so tightly fitted, they can take about a half hour to wiggle into, feet first.

The vocation is not just for the ladies.

Christian O'Brocki, or Merman Christian , attributes his interest in becoming a merman to watching the movie "Splash" as a kid. He put on his first tail four years ago, after spending half a decade acting professionally. O'Brocki acknowledges that working as a merman is "no swim in the park."

"I've been broke a couple times doing this job, but it always comes back to you eventually," O'Brocki says.

Demand for professional mermen is also more limited in a mermaid-dominated world, but O'Brocki is working to get people more excited about mermen:

"Why should the girls get to have all the fun?" O'Brocki says with a laugh, "For all the little merboys out there, I'm going to say if you want to wear a tail, you put that on, if you want to swim in the sea and be happy because it's fun, just go for it."

But whether they are at a landlocked swimming pool birthday party in Missouri or deep-diving in the Carribbean Sea, all the mermaids and mermen at Mermania see their profession as a platform to teach others how to respect and preserve the ocean and its creatures.

Fraser used the underwater performance skills she learned as a mermaid to create eco-activist videos such as "Manta's Last Dance," which ultimately helped put manta rays onto an endangered species list in 2014.

Having been up close and personal with so many kinds of oceanic wildlife in the past 13 years, Fraser realizes she would now risk her life for these animals. She hopes she can continue to communicate her love of the ocean to humans who have become scared or disassociated from it:

"By creating these images that show a connection and symbiotic relationship between humans and animals, people can find they can approach the ocean in an entirely different way: without fear."