MARINELAND, Fla. – Her eyes are cloudy now, a blueish-gray haze blocking out some of the sunlight that glints off the water in her habitat.

She doesn’t always move as nimbly as the dozen other dolphins sharing her space, either.

But that’s OK, because Nellie has something they don’t.

She has seniority – 59 years of it, more than double the normal age of an Atlantic bottlenose dolphin. And those eyes, before a hint of cataracts snuck in and stole the sharpness of her vision, have witnessed many of the triumphs, declines and rebirths of Marineland, Florida’s first theme park.

“She’s somewhat the matriarch,” says Kurt Allen, vice president and general manager of Marineland, as he watches Nellie gracefully glide under an archway in the pool where she is sunning herself on this severely clear May afternoon. “She is literally rewriting history every day.”

The same can be said for Marineland.

Now owned by the Georgia Aquarium, the world’s first marine animal park opened 74 years ago yesterday , offering visitors previously unheard-of access to dolphins, whales and other creatures that roamed the seas.

Bankrolled by a group of investors that included Cornelius Vanderbilt Whitney and Count Ilia Tolstoy (yes, grandson of Leo), the facility originally was called Marine Studios because it doubled as a location for filming underwater movie scenes.

On opening day, June 23, 1938, more than 30,000 people jammed the stretch of coastline 20 miles south of St. Augustine, their cars gridlocked on Highway AIA as they eagerly awaited the opportunity to glimpse the novelty that Marine Studios promised.

The eye-popping centerpiece of the park was a 75-foot circular concrete oceanarium where bottlenose dolphins and whales frolicked in remarkable proximity to the public. For $1.10, visitors could peer at schools of neon-hued fish and menacing sharks through 200 portholes that lined the venue’s walls.

From above, dolphins could be seen flaunting their tricks on the surface of the pool, and other aquatic creatures such as loggerhead turtles, sea lions and African penguins were elsewhere on view. Theme-happy watering holes such as the Moby Dick lounge and the Rocking Ship bar appealed to customers’ wallets and non-marine pursuits, and the flamingos near the front entrance made for colorful additions to visitors’ photo albums.

Meanwhile, the business of moviemaking got underway, and Marine Studios made its film debut with the 1939 MGM short, “Marine Circus.”

The site thrived as a movie set, appearing in several 1940-era “Tarzan” movies with Johnny Weissmueller and the 1953 documentary “The Sea Around Us.” Campy creature features filmed there in the ‘50s, including parts of “Creature from the Black Lagoon.” In the 1955 sequel “Revenge of the Creature,” hordes of screaming people can be seen tearing through the facility’s concrete stairwells, trying to outrun the plastic-faced monster.

Even the beloved Nellie, born at the facility in 1953 and now celebrated as the world’s oldest-living dolphin, can be seen on YouTube in a commercial with broadcaster John Cameron Swayze, demonstrating the resiliency of a Timex watch when she was just a few years old.

The motion picture industry continued to film movies on site well into the ‘80s, but in 1961 the facility’s name was changed in a marketing move. The tiny town that had sprung up around the park had incorporated as Marineland in 1946, and the owners decided to rename the venue after the town because it was marked on most Florida maps.

For decades, the pioneering aquatic retreat thrived as Florida’s only theme park, attracting as many as 400,000 thousand visitors a year during its heyday in the 1950s and 1960s.

But all of that changed with the fantastical vision of a man named Walt.

“The Mouse invasion,” is what Allen calls it. In 1971 Disney World opened, and suddenly the appeal of Marineland shriveled, overpowered by the irresistible allure of Cinderella’s castle and ice cream bars shaped like rodent ears.

Compounded by the opening of I-95, which funneled travelers away from A1A, and the arrival of SeaWorld Orlando in 1973, Marineland attendance deflated to 20,000 visitors a year.

Over the next several decades, the theme park would undergo a series of openings and closings, ownership changes and a bankruptcy. During that time the facility began to fall into disrepair. In 2001 Atlanta developer and Georgia Aquarium board member Jim Jacoby bought the property and closed it for a two-year renovation that included demolishing some of the original structures. It re-opened in 2006 as Marineland’s Dolphin Conservation Center with a fresh look – including a medical lab and eight new dolphin habitats -- and a renewed mission to educate the public about marine life.

But the restoration angered some of the Marineland purists, who cringed at the demolition of their childhood memories.

Gone was the original circular oceanarium, as well as the patented dolphin show. Also ditched was the infamous Rocking Ship Bar, a hangout of Ernest Hemingway’s thought to inspire “The Old Man and the Sea.” (The 41-foot bar is in storage now, but the author’s legacy lives on in Marineland’s newest arrival -- Hemingway, a spunky little dolphin born on site in September.)

Still intact is the replica of beige coral reef that marked the original entrance, the opening to thrust heads through for a photo op beckoning as always.

And the beloved statue of Neptune again presides over the garden near the front of the property.

“We always keep the history in mind when we plan things,” Allen says, pointing to another Marineland relic: an ivory building constructed of concrete blocks with dolphin cutouts that once housed the Fudge Kitchen. (The nostalgic can pack a block to go for $125 in the gift shop.)

Once the park reopened, attendance brightened slightly. In 2009, about 66,000 people visited. But in January 2011, Jacoby sold Marineland for $9.1 million to Georgia Aquarium, which renamed it Marineland Dolphin Adventure.

* * *

Across the street from the entrance to Marineland, in an unadorned building that doesn’t prompt a second look, George “Geo” Biedenbach, director of conservation programs, and field coordinator Matthew Denny spend their days doing the kind of work tourists may not think about when they visit the park, but which is vital to its dedication to marine research and education.

Opened in 2009, the $1.5 million Dolphin Conservation Field Station is a stranding center that rescues and recovers whales, dolphins, manta rays and whatever else might float to the surface or wash up on land.

In a back room, a rack of orange triage kits stocked with stethoscopes, medication and syringes are stacked up and ready to be snatched the moment a call comes in for a stranded whale or dolphin entangled in discarded fishing line. Entanglements can take several days and up to five boats to resolve.

Back at Marineland, they keep two boats at a new marina, one of them designed for dolphin pickups. They also have a pair of trucks, one used for transport that can carry up to 7,000 pounds and is equipped with two on-board water tanks and a food cooler.

Biedenbach and Denny respond to about eight strandings a year. The outcome usually isn’t pleasant.

“Seventy-five percent of the animals that hit the beach are already dead,” Biedenbach says. “Many others die on their own or are euthanized within 24 hours.”

If the animal is alive, the staff performs triage and transports it to one of its partner hospitals at SeaWorld, Harbor Branch Oceanographic Institute in Fort Pierce or Gulf World Marine Park in Panama City.

If it’s “fresh dead,” with no signs of bloating, it is taken to Marineland’s necropsy facility, located in a trailer in the parking lot behind the Guana Tolomato Matanzas National Estuarine Research Reserve, about a quarter mile from the field station. The small facility is a sterilized 24-foot car hauler that has been refurbished for medical use. A pair of stainless steel tables fills the width of the trailer, which is also equipped with rubber boots, aprons and hoses curled on wall hangers. Here, internal and external exams are performed.

“We’re basically ‘Dolphin CSI,’” Biedenbach says.

He and visiting veterinarians document lesions, signs of blunt trauma and other causes of death to glean what they can about underwater life. One of the discoveries they’ve made is that 40 percent of the adult pygmy sperm whales die from degenerative heart disease.

As an animal lover, Biedenbach has come to terms with the disconcerting sights and unpleasant necessities of his job.

“When I’m in the field I can put my game face on because I have to,” he says with a small smile.

But there are celebratory outcomes, too.

In 2010, the field station aided the aquarium in the transfer of five loggerhead sea turtles from the coast of North Carolina to the aquarium’s quarantine facility, where they were treated and released five months later off the beach at Jekyll Island.

And in addition to educating local school children on the environment, Denny’s primary project is identifying wild dolphins in the area and photographing their dorsal fins – a defining feature – so the animals can be tracked. If a dolphin becomes stranded or entangled, a zip through his computerized catalog can determine which dolphin it is, whether or not it’s a “resident” of the area and if it’s had other problems. So far Denny has collected and tagged data on more than 200 dolphins.

“This is a piece of the scientific puzzle that wasn’t happening before we were here,” Biedenbach says.

* * *

The Marineland of today operates as a separate nonprofit organization under the auspices of Georgia Aquarium. Located in a trio of nondescript off-white buildings battered by surf spray on about 7 acres of land, it is near the same spot where the original structures once stood, nestled between Highway A1A and a postcard-ready section of the Atlantic Ocean.

Georgia Aquarium has invested about $3 million into the facility so far this year, with the money mostly going toward operational improvements such as pool heaters and new signage.

Still, Marineland struggles to meet even a fraction of its former attendance figures.

Carey Rountree, senior vice president for sales and marketing at Georgia Aquarium, estimated that 50,000 people visited Marineland in 2011 and about 60,000-70,000 are expected this year. The eventual goal? To hit a six-figure attendance number again.

Rountree believes that public perception is the biggest obstacle, that many Marineland fans of years past think that once the venue closed for repairs in 2004, it never re-opened.

“That’s been our biggest challenge, to tell people, we are open,” says Rountree.

Despite the financial and attendance woes that have hindered Marineland, the Georgia Aquarium has a twofold stake in it.

The coastal Florida location provides access for additional marine research and collection – three of the four manta rays at the aquarium were gathered off the Marineland coast – and collaboration between the facilities allows the aquarium to answer critics who say the Atlanta aquatic emporium is too focused on entertainment.

“[Acquiring Marineland] really fit into the overall philosophy we were founded on,” Rountree says. “[Aquarium founder and CEO] Bernie Marcus wanted [Georgia Aquarium] to be a combination of entertainment, conservation, research and education. In order to do that, you had to pay the bills, and entertainment was a way to do that. Once we were able to pay the bills, we’ve been able to increase the education and conservation efforts.”

Earlier this month at Marineland, the “Behind the Seas” exhibit opened, featuring additional dolphin viewing areas, up-close fish encounters and a collection of artifacts from the oceanarium’s past.

While Marineland’s focus is on education, elements of the establishment remain tourist-y draws. Visitors willing to pay extra for intimate dolphins experiences can stand in shallow water for 20 minutes with the slate-colored mammals or be a trainer for a day.

After all, bills need to be paid there, too, owners say.

* * *

In the eight habitats overlooking the Atlantic Ocean at Marineland Dolphin Adventure, 13 bottlenose dolphins follow the commands of their trainers, presenting their fins to visitors who have paid for a “touch and feed” encounter. Some will later hold plastic containers of acrylic paints in their mouths and create dolphin Picassos for guests.

Meanwhile, one almost-sexagenarian dolphin cruises through the translucent water with a peaceful air. As she glides around her circular pool, Nellie glances at a visitor with a knowing look. She has endured the overwhelming crowds, the spotlight of Hollywood, the disrepair of her facility and now its revival with a focus on education.

No matter how cloudy her eyes have become, she is the lone inhabitant of Marineland who has truly seen it all and knows it’s been one wild ride.

If you go

Marineland Dolphin Adventure

Open daily 9 a.m.-4:30 p.m. Admission is $8.50 (adults 13 and older), $4 (children) and $7.25 (60 and older). 9600 Oceanshore Blvd., Marineland, Fla. (20 miles south of St. Augustine). 1-904-471-1111, www.marineland.net.