A group of children is on a field trip to Fontainebleau State Park in Mandeville. They wander along the shore line, taking in the sights when a young man approaches.

“I think I saw a mermaid over there,” he tells the kids. “Maybe if you yell for her she’ll come in.” The children take the man’s cue.

“Swim in, mermaid! Come on, mermaid! Where are you, mermaid?”

At first, all they see is a young woman’s head bobbing in and out of the water as she quickly swims toward them. When she gets close enough, Megan Larmann flaps her tail in the water, and the children go wild. It’s a real mermaid! In Lake Pontchartrain!

“Oh, my gosh! That is the best reaction that you will ever see,” Larmann says. “I’ve never had a kid tell me, ‘You’re not a real mermaid’ when we do that.”

The mermaid sighting is one of the services offered by Larmann and her sister, Emma, owners of Bayou Mermaids in Slidell. They put on their tails and take to water parks, private pools, Lake Pontchartrain or anywhere they can entertain and educate an audience.

On Sunday, May 2, at 6 p.m., the Larmanns will host about a dozen of their finned friends at an open-to-the-public “Swim with Mermaids” event in the Olympic-sized pool at the University of New Orleans Aquatic Center, 6801 Franklin Ave.

Children in swimsuits can join them in the pool for an hour or watch from sides. Swimming tickets are $15; spectators pay $5. Swimsuits are required, and flotation devices are recommended for children who can’t reach the bottom of the 4-foot shallow end. Tickets are limited and available online at Eventbrite.com.

“I’m a professional mermaid entertainer, along with my sister,” Larmann said. “My real passion is teaching kids about Lake Pontchartrain and about the animals that call our lake home. I do school visits, I work with nonprofit organizations like Lake Pontchartrain Foundation and the Lake Pontchartrain Basin Maritime Museum to raise money for their causes. And a lot of mermaids do that sort of thing as well.”

When Larmann isn’t a mermaid, she teaches middle and high school English at the Northshore Home Education Center, and her sister studies business at Southeastern Louisiana University. Megan Larmann is also a scuba diver and works part-time at a pet store.

“I was always attracted to (mermaids) because I very much love fish and I love being in that environment. I like to teach kids about the ocean. I volunteer at the Audubon Aquarium of the Americas. I’m the fish girl at a pet store. That’s where my love of mermaids comes from.”

Growing up with the lake as her playground didn’t hurt, either. The same goes for Venessa Lewis, owner of a Baton Rouge graphic design firm who’s also a professor at LSU.

Lewis grew up in Avoyelles Parish on the banks of Bayou des Glaises and later became the Louisiana Mermaid.

“I purchased my mermaid tail last year in the spring, and I started swimming in it in June just in local public pools because I don’t have my own pool. Through the wonder of social media, word spread fast about it. I had some Baton Rouge TV stations start showing up at those pools, and a couple of them did stories on me. I started getting all kinds of requests for appearances. I said, wow, this is way bigger than I thought it would be. I never intended this to be any more than a hobby,” Lewis says.

For the rest of the summer, Lewis says, she had bookings at local water parks and pools. By summer’s end, Lewis had signed on with the Livingston Parish Convention and Tourism Bureau to promote tourism, recreation and the parish’s waterways.

Lewis, Larmann and their fellow mermaids then found each other through word of mouth and Facebook. The local group isn’t alone. There’s an online forum for mermaids, MerNetwork.com, and a yearly convention called MerFest is held in Cary, North Carolina. This summer, Lewis is attending a Mermaid Portfolio Workshop in Isla Mujeres, Mexico, where photographers will capture her swimming with docile whale sharks, which spawn around the island at the end of July.

It’s all in a day’s work for The Louisiana Mermaid, who says it’s really not like work at all.

“There’s a lot of children from lower income families who are probably never going to experience the magic of, say, Disney World. They’re never going to meet Ariel or the Disney princesses. So they can just come out to a public pool or a public water park and meet a live mermaid, so to speak. It’s something that I love to be able to provide for them. They get to live that fantasy and experience that whimsy.”

The idea of being a mermaid may sound glamorous, and it can be fulfilling, but both Lewis and Larmann say it’s not for everyone. It can be costly — high-quality tails sell for about $3,000 — and physically demanding.

“You have to know how to swim and you have to know how to swim in the heavy tail that is holding your legs together. You can’t get claustrophobic or anything like that. It is the best workout that you will ever have. You do not realize how many muscles you have until you swim with a mermaid tail,” Larmann says.