Diane Cuniff’s dog spoke to her seven years ago, and she listened. Every time she’d drive down Pacific Coast Highway with Ajay, a fun-loving yellow lab, he would howl at the ocean.

He wanted to go for a swim.

Years later, Ajay’s aquatic interest proved prophetic for Cuniff.

After a series of twists and turns — 9/11, the dot-com bust — Cuniff’s life changed course. She left her job in high-tech sales because it was no longer stable and took a shot at flipping homes.

At one point, her purchase of a duplex in Corona del Mar became stalled in a six-month escrow. As Cuniff waited for the sale to be finalized, her mind kept cranking.

Ajay needed day care, and Cuniff couldn’t find a facility in Newport Beach, Irvine or Costa Mesa. So, just for fun, she decided to write a doggie day care business plan.

“I knew someone was going to make money doing this,” she said. “I just didn’t know it would be me.”

Fast-forward 16 years and Cuniff, now 65, is owner of The Bone Adventure, a dog care business with 80 employees and two locations: Bone Home, the smaller of the two, and Bone Backyard, with its piece de’ resistance — a $200,000 state-of-the art outdoor, heated, saltwater swimming pool built exclusively for dogs.

It’s the only one if its kind in Orange County, Cuniff said, “and would pass any inspection for humans.”

Ajay, who died five years ago at 15, would be proud.

The pool, at 2700 Bristol St., opened last year and has a client list of 200 and growing. The area surrounding the pool is heated to keep the dogs warm in the winter and landscaped with artificial grass for dogs that need a bathroom break.

The pool features a 40-foot-long diving dock, a shallow wading area, and every toy a dog could want, including inflatable rafts.

From glass-enclosed bleachers, visitors can watch the show — which is usually a mood-brightening comedy of carefree dogs pulling toys out of bins, frolicking in the water, and chasing balls and one another.

It’s most amusing when a dog refuses to leave the pool area after a session is over, hiding or jumping back into the water like a child not wanting the fun to end.

“You can’t come here and not be happy when you leave,” said client Janet Comer, who brings her two dogs, Cali, a 5-year-old black lab, and Rascal, an 11-year-old rescue dog, at least once a week. Rascal is part Staffordshire terrier, part Doberman, part cocker spaniel, part shepherd, and part wolf.

“We had his DNA checked,” Comer said.

Rascal has weak back legs and arthritis, and Comer said swimming has helped him a lot. “After Rascal swims he can jump on a chair,” she said.

Every day, several packs of about a dozen dogs bound through a door from the day care center into the pool area like ecstatic toddlers on a playdate. They are grouped daily by personality and temperament for 30-minute swimming sessions.

Most are day care dogs with their owners paying $10 extra for the pool perk. Outside visitors pay $25. Dogs have to be up to date on their shots and evaluated before they are accepted. Weaker swimmers need to wear life vests. The center has 23 webcams, with two in the pool area, so owners can watch the action.

There’s an endless supply of personalities and breeds. And Bone Adventure staff seem to know them all.

There are the Bullies who steal toys from other dogs (they shall remain nameless); the Gentle Giants and Happy-Go-Luckies — such as Andy, Charlie and Bear — who don’t want any trouble; the Screamers, including Gracie and Moose, who bark just to hear themselves talk; the Shallow Waders like Bennie Boy and Piper, who cautiously dip their paws; the Piranhas, such as Bo, Sadie and Enzo, who stop at nothing to chase a toy; and the Rowdies — including Vespa, Biggie, Nash and Asher — who enjoy life with gusto.

And there are the Dock Divers, like Lou Bug, Banksy, Sydney and Fletcher, who show off their athletic prowess as they take a running leap off the dock in pursuit of a toy. Banksy currently holds the long-distance title of 27 feet.

On a recent day, one excited visitor had an accident in the pool, causing it to close for an hour while staff sanitized the water. It’s a fairly rare occurrence, but Cuniff said it’s a drain on revenue because staff has to reschedule and cancel clients.

She maintains her sense of humor, however: She plans to make T-shirts saying, “It’s all fun and games until someone poops in the pool.”