Discovery Cove, the theme park known for swim-with-dolphin encounters and where most people arrive in aqua socks, is celebrating being open for 15 years.

The opening of Discovery Cove in 2000 marked the end of a period of rapid expansion for Orlando's theme parks.

Disney's Animal Kingdom opened in 1998. Islands of Adventure followed a year later at what was then branded "Universal Studios Escape."

Discovery Cove made its splash July 1, 2000.

"Quickly, we found out that Discovery Cove is no normal theme park," said Stewart Clark, the vice president of the park. "It was a weekend after opening when we realized they are not arriving later. They are all arriving very early in the morning. Our people really want to experience a full day in the park."

After 15 years, it's not uncommon for Clark to go home with sand in his dress shoes.

"Within that first six months that we opened, we realized the aviary was a home run for the park, and we actually expanded it," he said.

It's hard to see where the expansion connects to the original park today.

"We added two more aviaries shortly after we opened to give people more space and more birds to interact with," said Dave Eden, an assistant curator at Discovery Cove.

Other additions include an all-inclusive dining policy.

"The meal policy at Discovery Cove is something we may have missed at first," Clark said. "It took us a few years to realize we probably shouldn't charge someone for a bottle of water."

Breakfast, lunch, snacks and drinks are now included in the price of park admission. Clocks were later added so guests could get to their dolphin interaction programs on time.

Discovery Cove limits reservations to 1,300 people per day. That limit guarantees one-on-one time — which was basically unheard of when the park first opened.

Dr. Duncan Dickson, an associated professor at the Rosen College of Hospitality Management at the University of Central Florida, teaches the business of theme parks.

"It was a calculated risk that has proven to be extremely successful," Dickson said of Discovery Cove. "It's hard to get in. People are willing to pay for that experience."

And that experience is evolving.

"Our goal here is to continuously improve," Clark said.