and it's not filled with chlorinated, treated water.

This is a natural spring in Weeki Wachee, Florida.

And it's at the top of a massive system of caverns,

where the Weeki Wachee River surfaces.

Hundreds of millions of litres of water

forcing its way out the ground every day.

But while the spring might be natural,

what's going on under the surface definitely isn't.

It's created by humans, because for more than 70 years,

there's been a mermaid show here.

- Toughest part of the job, I definitely think, is training.

Took me about six months to swim my first show.

Once you get hired, you get scuba certified

and then you can start on the hose, which --

that's the process that takes the longest.

Learning how to breathe and be comfortable down there.

It takes a lot of breath control and building your lungs.

Teaching your lungs and stretching them and getting them used to holding the air.

The longest we hold our breath here is the Ferris wheel.

That's when we hold each other and we spin around.

The water is 74.2° year-round. It's very cold being in there.

- We have approximately 20-25 young women on staff

who perform as mermaids.

We also have about three or four gentlemen

that play the role of the prince in our version of The Little Mermaid.

- This place is the work of a man called Newt Perry,

world class swimmer and swimming coach,

former diver for the U.S. Navy, and consultant to Hollywood.

He looked at this spring and thought,

"I could put a show on in there".

The first theatre had 18 seats, but by the sixties,

the ABC television network had bought the place,

and built a theatre for 400. And it was selling out.

- Well, 117 million gallons of water

coming from a very tiny opening at the bottom of the spring on a daily basis

will provide a current, and it's about a 5mph current.

They're not swimming in a tank.

There's so many different species of wildlife that inhabit a Florida river, we get 'em all.

Turtles, otters, the manatees are always a favourite.

- The turtles love to get in the way,

and they'll follow your tail around.

We don't really have snakes come that often.

Every once in a while, blue moon.

And then sometimes we'll get alligators.

If they're in a range that's too close,

we'll get out of the water.

- In the 60s, Weeki Wachee was a spectacular, world-famous tourist attraction.

But by the 90s, the consensus was that is was a relic.

Dated and down on its luck, at least compared to the shiny new theme parks

that Disney and Universal were opening over in Orlando.

In 2003, the New York Times called this place "aging" and "faded".

But it turns out that once something gets old enough,

with the right marketing, "outdated" can become "retro". "Historic".

- Weeki Wachee Springs was a private company

all the way up until 2008, when the state of Florida,

in an effort to help save it, acquired the attraction.

And not only did they acquire it

for the natural resource that we have here, the spring,

the scrub habitat that surrounds the spring,

but also because of the cultural significance

of what the mermaids have meant to Florida tourism for seven decades now.

- Weeki Watchee is never going to be on same level as Walt Disney World.

It couldn't be.

But the same day I'm here, the Florida state tourist board have sent a crew to film.

The last audition call for mermaids here made the news around the world,

and the articles are sounding a lot more positive than they did 15 years ago.

In the 21st century, Weeki Wachee is becoming a bit of living history.

History that still has three shows a day.

- Being a mermaid is the best job anyone could ask for.

My favourite part of the job is dealing with the kids

and making a difference in the community.

We do a lot of dealing with Make-A-Wish programmes,

and these kids think that you're really a mermaid

and they think that everything you're doing is so magical.

Just making such a difference in their lives,

just by coming to work,

we're pretty lucky that we can do that.

- Thanks to all the team at Weeki Wachee Springs State Park.

You can find out more about them at the links in the description.